I've had an ongoing issue that has my GM XLR-Certified Master Technician mystified. I have an 05 XLR 30K miles that randomly displays the "Service Engine Soon" light in the DIC when I start it. This weekend it came on and I went directly to the dealership, message displaying in the dash. trouble is there are no codes whatsoever in any of the computers. I was told that for a message to display a code needs to activate it, but not in this car... This has been continually happening for several months, but no codes. Has anybody seen this before, or are there any ideas? My tech is stumped.

I've had an ongoing issue that has my GM XLR-Certified Master Technician mystified. I have an 05 XLR 30K miles that randomly displays the "Service Engine Soon" light in the DIC when I start it. This weekend it came on and I went directly to the dealership, message displaying in the dash. trouble is there are no codes whatsoever in any of the computers. I was told that for a message to display a code needs to activate it, but not in this car... This has been continually happening for several months, but no codes. Has anybody seen this before, or are there any ideas? My tech is stumped.

I work with marine applications of the "Kavassor Kan Kingdom" systems, similar to those used within our cars. As to the 'fault status', an inoperative O2 sensor would creat a 'sticky fault', but a sudden dip in voltage or current would not. That short burst of low power is considered a 'non-sticky fault'. Also that sudden burst of low power may trigger the exact problem you describe. A low power/intermitent (shorted plate) battery, or a loose battery cable connection may be your only mechanical problem. While cranking the motor many electronic systems are 'waking up' and that also takes power. Each of the electronics systems in the car has it's own "power stabilizer" built into that component, to ward off overpowering and UNDERPOWERING the fragile 5V DC electronics. Starter, solinoid, fuel injectors, fuel pumps, spark/coils/ignition, engine ECM and on down the line, all take at least 11 V and good steady current flow from + to - or in the actual physical action electrons going from - to +. Check all your main power cable connections and swap batteries for a few 'test days'. Good luck.

Did you replace he battery recently?? I can't recall.

If not I think CC suggested that a failing battery would cause this condition. So AzGeo may be on to something. A load test just may highlight the battery issue and solve the light issue.

We batted this around in another venue and the general consensus is since the message is generated by the ECM and sent to the BCM for display, both are suspect, with the BCM being 51% more so. The dealers are loathe to replace (expensive) components that aren't specifically called out by Diagnostic Trouble Codes, and swapping (--components, that is!) is frowned upon, so it's a tough call. This issue isn't common, but several owners have reported the same symptoms. A BCM replacement fixed one of them.

Filtering circuits in digital system's power supplies are supposed to deal with transients, but all it takes is a little EMI to make a digital bus go apesXXX. Aging components, microscopic etch flaws in vibrating environments, weak solder joints, etc all add up, making troubleshooting integrated systems that don't display fault codes a job for knowlegeable techs who really understand how a circuit is supposed to work when standard troubleshooting flows don't apply. These kinds of faults seperate the good techs from the great (and/or lucky) techs.

Anybody else out there have any similar problems/fixes?

CC :cheers

Great info. the battery was replaced several months ago when the original failed. That left a bunch of codes in history that have been cleared two visits back. I'll check the cables just to be sure. This is its 8t visit and several repairs later to clear the this message. I work with computer and know how they can have quirky failures, so I'm leaning towards one of the modules. Consensus is the BCM. I can order the part from GM, only $264 and it can be removed and replace with 3 screws and 2 connectors according to the service manual. The catch is, it then has to be programmed with the VIN number using the GM Tech tool, once again eliminating the home mechanic from doing repairs. Also have to clear any codes set by the initialization. I'm waiting for the dealer's estimate, they keep talking about how expensive the repair is... other than the reprogramming it's a simple job. This is frustrating on many levels, putting a damper on my love affair with the XLR.

You're right. DIY-wise, you're totally dependent on a dealer to perform routine troubleshooting tasks with a Tech 2. Labor-wise, they shouldn't soak you (as opposed to won't soak you) since BCM replacement/programming is pretty easy. Maybe twenty minutes to remove/replace, and ten to load the new numbers and run a full diagnostic. Clearing stored codes is one keypad press. It isn't rocket science, --but then, you're not supposed to know that. See if you can get a realistic labor estimate from the Service Advisor by explainng the replacement process in the Service Manual. Their labor books are pretty realistic, unless they're cross-eyed and dyslexic, and then any number may appear. This way, they can't try to snow you by pretending the whole repair process is mysterious/expensive or hide behind their dyslexia.

One way to save a few bucks is buy the BCM yourself (saving around 40% in the process) and have the dealer install it. Mine wouldn't warranty the (OEM) parts I bought online, but would warranty their labor, so it worked out. After a couple of cycles of that, I sprung for a Tech 2 and haven't been back since. (Of course, the car knows I'm armed and hasn't had any real issues either!)

:cheers CC

Maybe i should buy a Tech 2 and she'll behave :jester

Thanks for the advice, I've called for estimate and made it clear I'm not happy with 8 trips to the dealer, maybe they'll play nice. If the Service advisor quotes to high, I'll move up the chain of command. The only problem I have is that it's the only dealer nearby with an XLR-certified tech.

Thanks to all who posted some advice, here's to you :cheers

I'll keep you posted

We batted this around in another venue and the general consensus is since the message is generated by the ECM and sent to the BCM for display, both are suspect, with the BCM being 51% more so. The dealers are loathe to replace (expensive) components that aren't specifically called out by Diagnostic Trouble Codes, and swapping (--components, that is!) is frowned upon, so it's a tough call. This issue isn't common, but several owners have reported the same symptoms. A BCM replacement fixed one of them.

Filtering circuits in digital system's power supplies are supposed to deal with transients, but all it takes is a little EMI to make a digital bus go apesXXX. Aging components, microscopic etch flaws in vibrating environments, weak solder joints, etc all add up, making troubleshooting integrated systems that don't display fault codes a job for knowlegeable techs who really understand how a circuit is supposed to work when standard troubleshooting flows don't apply. These kinds of faults seperate the good techs from the great (and/or lucky) techs.

Anybody else out there have any similar problems/fixes?

CC :cheers

You are sure that this problem is from within the ECM or BCM ? No small 'split second event' anywhere thruout the 'can network' could effect the ECM in this way ? I'm finding it hard to understand how a BCM internal problem would not 'throw any codes' when the ECM is still operating the car/motor in normal fashion. First of all, it happens "at start up", I read nothing about any other operational activity. Second, the "Service Engine Soon" warning is directed to 'engine only questions' and not 'body' or 'accessory' related. The ECM (as I have quickly read on line) is the 'king' of this vehicle's 'domain' and has 'rule' over the BCM. (right ?) This means that IF the BCM WANTED to DO ANYTHING, the ECM would be required to allow the BCM to do that action. The ECM sends a signal to the BCM, put the "SES lamp" on. The BCM reads that signal, sends a reply 'yes I put on the "SES lamp" (in English or other) right now. The ECM would reply 'OK' handshake. "Signal sent, reply/action, handshake". IF the BCM (were malfunctioning) sent/action "SES lamp", the lamp would come on, the reply back to the ECM would be sent at the same time and the ECM would NOT OK HANDSHAKE, it would throw a code. Because the ECM didn't send any signal for any action/reply to the BCM. IMHO, the ECM can and will operate without the BCM functions operational, but the BCM cannot function without the ECM. Correct ? I offered the above insite because I know that the "GM and Mercury Marine" can systems are almost identical in structure and software. GM designed both/all of these systems. Along with the fact that I have found this problem in the Mercury Marine DTS systems. (fly by wire) It's a long story, but it did take over 75 hours of testing (3 months) of "one change/test" at a time.

"The ECM (as I have quickly read on line) is the 'king' of this vehicle's 'domain' and has 'rule' over the BCM. (right ?) "

The BCM is the gateway between the GMLAN and Class 2 bus. One of its (many) functions is to emulate all of the high-speed GMLAN modules on the Class 2 serial data circuit. It transmits multiple Node Alive messages using source IDs that reflect each GMLAN node, which includes the ECM. The ECM monitors all engine-related sensors, performs diagnostic checks, and alerts the driver by illuminating the Multi-Function Indicator Lamp, (MIL) while setting a Diagnostic Trouble Code (DTC.) The MIL command is passed to the BCM via GMLAN, then placed on the Class 2 bus for the Instrument Panel Cluster (IPC) to display. --This is the nominal path.

The BCM only responds to commands (data request/acknowledge/DTC/Health & Status) in this regard. (It deals with power distribution control too, but that isn't the issue here.) There is no King, per se. Just data packets gathered by controllers monitoring specific functions and passing them to the BCM for display on another bus. While this architecture uses the CAN, (Controller Area Network) it also has to work in tandem with the slower Class 2 bus, on which the BCM serves as an arbitrator.

In complex digital systems, there are soft faults, (produced by glitches and timing errors and are usually intermittent) hard faults, (that set codes and can be more easily resolved) and system anomalies (persistent/un-resolvable and cause no system degradation, --just operator annoyance.)

In this case, with an illuminated MIL and no DTC, a system tech needs to look at the operating parameters of the engine to ensure its within specs to determine whether the ECM is seeing a potential fault or flagging the bus with a non-existant error. A sensor on the very ragged edge could conceivably trigger the ECM's diagnostic parameters without setting a DTC, but I think this car is pretty well engineered (diagnostics-wise) and since the vette electronic systems shares so many similarities, (They even share the same module IDs on their respective GMLAN and Class 2 buses.) bad parameters would be more evident on the combined production of both vehicles, --especially with the larger number of vette's produced. Being a distant cousin has some benefits. Glitches found on the higher-production vettes may trickle down as future firmware updates for us.

The ECM and BCM are both suspect. Come to think of it, the the IPC could be erroneously turning on the MIL; weirder things have happened. Since I've heard of the BCM fixing the problem with the same symptoms, I'd give it a 1% differental between the two (ECM/BCM.) Of course, this is all speculative on my part. I'm just some knucklehead, sitting around in my boxers, swilling beer when I should be in bed, sleeping fast for my day job. I'm not sitting in the car with a Tech 2 plugged in to see for myself. If the problem gets resolved and we get feedback, then we'll know for sure, and can place the fix in the knowledge base and our collective noodles.


:cheers CC

CC and AZGeo:

You guys are well beyond my simple and aging brain here. BUT I am wondering if there may be similiar issues over on the Corvette site. The guys over there are easy to talk to and since there are more Corvettes on the road we just may turn up the anomoly were are looking for.

Just saying......

Just a clarification based on AzGeo's comments. The message is Service Vehicle Soon in the DIC, not Service Engine Soon, and there is no engine light. That basically eliminates some of the engine operations and emissions systems as the culprit according to my dealer's technician. He also told me, though the message appears at start up, that doesn't necessarily mean the code was not set previously. Apparently some messages appear immediately and others don't? I'm not a mechanic but that seems strange to me, however it was the case back when I was having mass air flow issues earlier in my ownership. Then again there are no codes being set in this instance, so who knows what this car is thinking. It's been two days since I heard from the technician or my service rep, so that may not be a good sign.

[QUOTE=majik755;39729]Just a clarification based on AzGeo's comments. The message is Service Vehicle Soon in the DIC, not Service Engine Soon, Thank you, I stand corrected. However, I do (now) understand your terms, such as "GMLAN" or "Class 2 Bus". We have different names for the "Bus circuits" but it is the same basic system. (GM designed) When I mentioned "King" refering to the ECM, I was speaking about the overall control it has over the entire system/vehicle. Redundancy and self diagnosis are the key factors within all of the ' classes of Bus systems'. Since all of the different components of this multiplexed system run on the same 'speed and signal language', the different levels of systems do speak to one another all the time. The BCM feeds info to the ECM as it is programed to do, and the ECM 'looks at all the functions of the engine and body' constantly. With an operational ECM, but a non-operationl BCM the car will start and run. But, if the BCM is functioning and the ECM is not, the car will not run. The ECM can also transmit incoming data/responce on any bus and transfer that data to another bus. The ECM can also search thru all the bus systems to find 'missing data' from a malfunctioning bus circuit. Redundancy. Also the BCM gets it's 'wake up' from the ECM turning on the main power relay (s). I'll bet the throttle activation is part of the 'class 1 bus', but has an override built into the 'class 2 bus' (in the stop lamp or cruise control off circuits) Redundancy for partial failures too. We have only 4 levels of 'bus class' in the marine side, does this car go on with other 'bus class' levels ? (5/6/7.....)

AzGeo,

XLR has two distinct buses tied together by the BCM. A failure in either the BCM or ECM can prevent ignition. The Distance Sensing Cruise Control module/Engine Control/Transmission Control/Electronic Brake Control modules are tied into the high-speed GMLAN bus due to their critical time-sensitive, integrated functions.

If the DSCC module see a target within it's range gap, it places a "Warning Will Robinson!" message on the bus. This would qualify as a top priority flag. The TCM may downshift, the TCM may slow the engine revs and and the brakes may be applied, depending on range rate (opening or closing) and distance to the target.

One of the few redundancies within the network is the BCM. If the RCDLR fails (can't see a fob to let the BCM know it's time to start the car) the limp-home antenna is wired to the BCM.

The ECM doesn't look at body functions, it just processes engine-related sensor data and accepts throttle control commands.

All kinds of data is placed on the network for any module that needs it. Ambient air temp sensor data may be required for the HVAC module to cool the car to a set level at ignition; if the cabin microphone noise level gets to a certain point, it's value will be factored into the noise compensation adjustment to the sound system --if that feature is enabled. If the window position count doesn't correspond to them being fully lowered when commanded, the Folding Top Control module won't permit the top to move. The list is mind-boggling.

One purpose of the BCM is to ensure both buses are getting messages back and forth to whatever module needs it. It monitors status and health from each module which is transmitted at regular intervals.

You're right, the ECM can transmit data to either bus, but it has to go through the BCM to do it. There is no Class 1 bus however. I'm sure you have other names in the marine world for the different buses used. For XLR, it's two: GMLAN and Class 2. Both are integrated into a Controller Area Network, which is why a CANDi module is required with a Tech 2. I hope I'm explaining this in a way that makes (some) sense.

:seeya CC

AzGeo,

XLR has two distinct buses tied together by the BCM. A failure in either the BCM or ECM can prevent ignition. The Distance Sensing Cruise Control module/Engine Control/Transmission Control/Electronic Brake Control modules are tied into the high-speed GMLAN bus due to their critical time-sensitive, integrated functions.

If the DSCC module see a target within it's range gap, it places a "Warning Will Robinson!" message on the bus. This would qualify as a top priority flag. The TCM may downshift, the TCM may slow the engine revs and and the brakes may be applied, depending on range rate (opening or closing) and distance to the target.

One of the few redundancies within the network is the BCM. If the RCDLR fails (can't see a fob to let the BCM know it's time to start the car) the limp-home antenna is wired to the BCM.

The ECM doesn't look at body functions, it just processes engine-related sensor data and accepts throttle control commands.

All kinds of data is placed on the network for any module that needs it. Ambient air temp sensor data may be required for the HVAC module to cool the car to a set level at ignition; if the cabin microphone noise level gets to a certain point, it's value will be factored into the noise compensation adjustment to the sound system --if that feature is enabled. If the window position count doesn't correspond to them being fully lowered when commanded, the Folding Top Control module won't permit the top to move. The list is mind-boggling.

One purpose of the BCM is to ensure both buses are getting messages back and forth to whatever module needs it. It monitors status and health from each module which is transmitted at regular intervals.

You're right, the ECM can transmit data to either bus, but it has to go through the BCM to do it. There is no Class 1 bus however. I'm sure you have other names in the marine world for the different buses used. For XLR, it's two: GMLAN and Class 2. Both are integrated into a Controller Area Network, which is why a CANDi module is required with a Tech 2. I hope I'm explaining this in a way that makes (some) sense.

:seeya CC

I do thank you for some insite as to how this car works, but it seems to me that all of this still backs up what I have stated above. As you point out "the BCM is the junction box for all of the data (body function data) being processed on the line. Your "GMLAN" is just called "can one" in marine use. Let's try to simplify what is going on here. At the press of the GREEN LIGHT, the ECM TURNS ON THE MAIN POWER RELAY, correct ? This in turn turns on all the other BCMs and control modules within the car, right ? Did you know that we have 'joy stick controls' in our marine electronic systems ? These contols can actually PARK a twin engined boat at the dock without steering input ? Our cars are complicated, but the boats I work with use the same exact electronics and they are far from simple. YES, there are a great amount of electronics envolved in these cars, but taken 'ONE BY ONE' each system can be broken down to it's simple basic roots. "It's only 1's and 0's !"

"At the press of the GREEN LIGHT, the ECM TURNS ON THE MAIN POWER RELAY, correct ?"

---No. Pull the toe board cover back on the passenger side. That is the BCM. It contains numerous relays and fuses (in addition to the UBEC under the hood.) The ECM only deals with the engine.


"This in turn turns on all the other BCMs and control modules within the car, right ?"

---No. There is only one BCM. and yes, primary power is applied to all modules at power-up.

"YES, there are a great amount of electronics envolved in these cars, but taken 'ONE BY ONE' each system can be broken down to it's simple basic roots. "It's only 1's and 0's !" "

---Absolutely! The old adage, "How do you eat an elephant?" "One bite at a time." certainly applies with integrated systems.

:cheers CC

Another BIG difference between ECM vs BCM. The programming that controls the ECM can be flashed and updated by the Tech when necessary, and there have been some mandatory updates to the 2005. According to my Tech at Cadillac, that's the big problem with the BCM. It's programming is burned in, and not updateable; that's why it quickly becomes the culprit in investigations, and is only resolved by replacement. There was an issue years back when the BCM flooded the system with voltage fluctuation codes and the driver could not get the car in gear, a failsafe system in the program. Turning off and restarting with stop the flood of codes and the car would start. The only solution was to replace the BCM. Obviously not my problem, I get no codes; but that problem brought to light the fact that the BCMs programming could not be updated. Still waiting for a response from my Service Rep and Tech. Starting to get my pressure up, oh well :cheers

I've had an ongoing issue that has my GM XLR-Certified Master Technician mystified. I have an 05 XLR 30K miles that randomly displays the "Service Engine Soon" light in the DIC when I start it. This weekend it came on and I went directly to the dealership, message displaying in the dash. trouble is there are no codes whatsoever in any of the computers. I was told that for a message to display a code needs to activate it, but not in this car... This has been continually happening for several months, but no codes. Has anybody seen this before, or are there any ideas? My tech is stumped.

There has been a lot of discussion on this, but you don't seem any closer to a solution.

A couple of questions:

1/ Do you have an actual text message telling you to get your XLR serviced, or is it the amber engine shaped light (called the Malfunction Indicator Lamp - MIL) that is on (or both)?

2/ Have you tried a different Tech-2?

The fact is that if you get that light you either have a fault code somewhere or you have a fault in the wiring. Are you sure you don't have U1000 or something?

The most common reason I know of for no fault codes (when there should be codes) is that they have been reset, usually through a power failure (i.e. a loose connection or similar).

If it is the MIL lamp that is on and no message, then a short to ground in the lamp wiring is indicated. There is a section in the workshop manual on that. Start with the index under 'MIL always on' and go from there.

I have a 2004 XLR, these notes are taken from that w/s manual.

As a summary, the opening move (after a basic check) is to disconnect the ECM. The MIL is an LED and is grounded by the ECM on C1-24. The good news is the signal passes through the underhood fuse block (don't know why), in my manual it comes in on C3-C2 and goes out on C2-F1.

If you have the service engine lamp lit (and it is down to a fault code), then it should be an emissions problem and that can be scanned by any old scan tool (isn't that the point of the standardised codes that came with OBD-II in 1996?).

BTW, if the MIL is flashing, the fault is serious and you should stop driving.

The only message is the "Service Vehicle Soon" message in the DIC, the engine light does not come on, no codes in any of the memories, ECM, BCM, TCM. Had codes in the past, all were resolved an cleared with prior repairs. This is something new and produces no codes.

Don't know if my Dealer technician has tried another Tech2, but it works on all his other cars and repairs.

There are also no symptoms with the car. I'd just ignore it, but according to the manual the SVS message is serious and the car should be brought to the dealer. The message appears every couple of days or so when I turn on the car. Unfortunately the dealership wants nothing to d with the car unless the get a code. I've stopped by several times, with the message in the DIC and without the message, so far no codes. If I press reset, or restart the car the message goes away.

The only message is the "Service Vehicle Soon" message in the DIC, the engine light does not come on, no codes in any of the memories, ECM, BCM, TCM. Had codes in the past, all were resolved an cleared with prior repairs. This is something new and produces no codes.

Don't know if my Dealer technician has tried another Tech2, but it works on all his other cars and repairs.

There are also no symptoms with the car. I'd just ignore it, but according to the manual the SVS message is serious and the car should be brought to the dealer. The message appears every couple of days or so when I turn on the car. Unfortunately the dealership wants nothing to d with the car unless the get a code. I've stopped by several times, with the message in the DIC and without the message, so far no codes. If I press reset, or restart the car the message goes away.

According to my 2004 w/s manual, "Service Vehicle Soon" on the DIC is raised by the ECM for a non-emissions related problem.

This means that you can get it for about three reasons I can think of:

1/ You have a non-emissions related fault code in the ECM
2/ You have a faulty IPC (i.e. it is making it up)
3/ You have some other problem.

Of these I lean towards 3/. Given you can't find any fault codes stored in the ECM, I am thinking you might be having power problems, either during crank or shortly afterwards (these could cause the ECM to erase a stored code).

1/ I would have the ECM connectors removed, cleaned with contact cleaner (DO NOT USE WD-40) and firmly push them back into place

2/ I would look really closely at the battery performance, including proper terminal cleanliness.

Put a data logger on the battery cables and measure voltage (not on the actual battery terminals), or perhaps measure voltage in the cigar lighter. Watch the voltage during crank. You really don't want to go much below 12v, maybe 11v. 9.5v is the absolute minimum, but a good battery should do better than that.

Can you confirm that when you switch off after driving, the odometer displays for around 20s?

I would then get your dealer to loan you an ECM. I don't understand why they refuse to diagnose an XLR arriving at their service center displaying the message that the ECM is reporting a non-emissions fault. Seems pretty basic to me.

Thanks for the analysis. Had battery issues a while back, now its a new battery and I checked the terminals to ensure they are tight and clean. The tech did check the battery and voltage was great according to his reading and seems fine any time I check it. All looks good in that area. I know the RAP system works, retained power seems OK, I'll look for the specific odometer reading you've indicated.

Know idea about the ECM. Next time it's in the shop I'll ask the tech to more thoroughly explore the specific areas you've identified. As I've said he seems o lean to the BCM, but without any real solid reasoning, other than there have been some problems in the past due to programming (though the symptoms are far from mine) and there is no way to reprogram it, it must be replaced.

Thanks again for your thoughts and research. I appreciate your help and the other is this forum as well.

Steve

I am going to assume you did replace the gas cap already and/or ensured your current one was put on correctly. I won't tell you why I know the latter.......

Also to reset the indicator remember the post that said it took ...I think 3 times on/off to recycle.

Regards

I have been following this thread and want to share my electrial experiences with my '06. I have had it for just over 2 years without any major problems. I have had several minor glitches with the top and trunk - trunk will not close using button, trunk will not open properly, etc. (and yes I do have the latest top programing)

I put about 5000 miles a year on the car with a mix of short and long trips and have not had any battery problems, but decided to get a Battery Tender last fall (local auto parts store had a special!). I was supprised to find that it took nearly a week to bring the battery up to full charge!

Now, although I have only had it out a few times this spring, I am finding that there are not little glitches with the trunk or top and am wondering if these cars are that sensitive to even a slightly less that fully charged battery. I will keep a watch on this and post anything I observe throughout the spring and summer. Maybe a Battery Tender should be standard on XLRs:rolleyes!

Xlrlist01


Checked under the hood and battery cables are tight, my battery tender indicates 13 + volts, battery is only about 3 months old, so all looks good in that area. When I shut the car off the odometer continues to read for about 15 secs. All seems well except that the Service Vehicle Soon message randomly appears about every 5 - 7 starts.

I emailed the dealership, both the tech and the service rep. Pointed them to this site and asked for an assessment on what to do next. If they don't have any ideas I'll escalate to the Service Manager, but it seems knowledge or more pointedly support for the cars at the GM/Cadillac level is weak. Hopefully the tech still has some connections around the country.

I'll keep you posted.

Xlrlist01


Checked under the hood and battery cables are tight, my battery tender indicates 13 + volts, battery is only about 3 months old, so all looks good in that area. When I shut the car off the odometer continues to read for about 15 secs. All seems well except that the Service Vehicle Soon message randomly appears about every 5 - 7 starts.

I emailed the dealership, both the tech and the service rep. Pointed them to this site and asked for an assessment on what to do next. If they don't have any ideas I'll escalate to the Service Manager, but it seems knowledge or more pointedly support for the cars at the GM/Cadillac level is weak. Hopefully the tech still has some connections around the country.

I'll keep you posted.
Cadillac has a national/international online knowledge database support system for issues like this and the repair "How To" bulletins that are issued for the XLR's 2004 through 2009.

If they haven't looked there for your issue it would be a good idea. I am not ready to believe you are the only XLR with this problem.

Regards

The tech finally emailed a response to me. He looked at the threads here and elsewhere, but strongly believes the ECM is not involved. If it were he says it would be the Service Engine Soon and/or Engine Light depending on whether it was emissions or not. Because it is the Service Vehicle Soon light he believes it is being set by the BCM. He has showed me several issues with the BCM, but nothing matched. I assume they came from the database. He found nothing that displayed the message without a corresponding code. He also let me know that GM has gotten lax in their documentation, and with these vehicles there is no documentation that lays out what error creates this display message in the DIC. In the past things were very well documented, now they have to search through every system to trace a problem. He's hasn't received a response from the GM rep in charge of the XLR technical team, but of course they are onto other jobs now. He's supposed to try again and get back to me today. I'll keep you posted. I've yet to deal with the Service Manager directly, but its getting close.

Well at least they are trying to obtain an answer for you.

We need to remember that the electronics are also to some extent used on the Corvette and other GM models. So I am wondering if a "search" on those GM Propiatary databases would turn up your solution.


We'll get a solution soon.

Regards

Didn't think about our "cousin" cars, the Vettes. My buddy has an 08, I'll have to see if his service manuals talk about the "Service Vehicle Soon" message in the Vette. Not sure they have an equivalent message area, but its worth a shot. Maybe there will be some more detail there.

Thanks

Steve

Xlrlist01


Checked under the hood and battery cables are tight, my battery tender indicates 13 + volts, battery is only about 3 months old, so all looks good in that area. When I shut the car off the odometer continues to read for about 15 secs. All seems well except that the Service Vehicle Soon message randomly appears about every 5 - 7 starts.

I emailed the dealership, both the tech and the service rep. Pointed them to this site and asked for an assessment on what to do next. If they don't have any ideas I'll escalate to the Service Manager, but it seems knowledge or more pointedly support for the cars at the GM/Cadillac level is weak. Hopefully the tech still has some connections around the country.

I'll keep you posted.

The 13V is good, but that is with the tender switched off isn't it? The reading of a battery that has been recently charged is useless, you need to run the headlamps for a few minutes (5 or so) to remove any surface charge on the battery plates and then measure the voltage.

However, not withstanding a new battery (could be defective, these things happen), it is the voltage at crank that matters.

In a different post it is stated that the w/s manual does not identify the source of the SVS message. Well my 2004 manual does. It is quite explicit and states that it is raised by the ECM for a non-emissions related problem. (This is on the right hand page, opposite the left hand page that is useless about the SVS message!)

I really don't think the BCM comes into this at all, unless there is an error in the w/s manual of course.

I would still have the terminals of the ECM cleaned and then if that does not fix it, borrow an ECM (after checking voltage during crank). As I have said, the most common reason I know for an equipment to not have stored fault codes when it should is either a power drop out has erased them or the equipment is faulty. In this case it is your ECM that is suspect.

Just for the record, I had a GM car with a defective ECM many years ago, when it failed on a journey (for about 60 seconds), the only hint was the car dropped out of overdrive, the backup systems were so good there was no obvious driveability problem. No fault codes stored then either!

Thanks again, I think I'll just make sure the connectors on both the ECM and BCM are cleaned and reseated. After all, one guy says he replaced the BCM for repair, and he may have just effectively cleaned the connectors. May be a silly question, if the car is turned off and battery disconnected, and I then remove and clean the connectors, will it affect either of the modules and require resetting via a Tech2 or will they just reinitialize and work fine. I'd hate to do-it-myself and need the car towed rather than drop it at the dealer and pay to have it done. My gut says they should be fine, but with these cars you never know :rolleyes

If you are going to do this I would also recommend you apply some electrical contact grease to ensure no moisture gets in.

A visual inspection of the BCM connectors wouldn't hurt. Applying some contact cleaner might not be a bad idea either. You shouldn't need a Tech 2 if you're not replacing it.

An old TSB:

Component Description:
67. ELECTRICAL SYSTEM Bulletin Number: 4094
Bulletin Date: Jan 2001

Vehicle: 2,005 Cadillac XLR
Summary:
ELECTRICAL CONCERNS - WATER LEAK ON THE PASSENGER FLOOR OR BCM AREA. ( NHTSA ITEM NUMBER - 10020052 )

A new BCM is available on ebay for $140. A Tech 2 is required to complete the installation.

http://cgi.ebay.com/ebaymotors/2004-2005-Cadillac-XLR-Body-Control-Module-BCM-Fuse-Box_W0QQcmdZViewItemQQhashZitem2c508dfacfQQitemZ19 0330043087QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcce ssories


:cheers CC

After almost a year of this problem and 8 trips to the dealership paying for parts and losing use of my car from 3 days to a week and half, still no resolution :cry

Here's two emails I got late last night and early this morning from the technician at my dealership after forwarding him some of the info I've collected here. This is frustrating.

email#1

"I can see them using the SVS message on an early failure of a PCM/ECM code, however they are required by ANSI to store freeze frame/fail record data when any code sets. I am not sure if we checked for ff/fr data even though the computer said no codes. we might try that next time you come by.

On most cars the SVS message is reserved for body functions, but like I said before engineers kind of do whatever they want since there are no laws around the use of this indicator/message. Please keep reminding me to do some research and feel free to stop byand I'll check the codes and freeze frames again.

email #2

There is a bulletin on some cars for certain issues to remove the connections, make sure they are clean and apply some dielectric grease. I have done it on a couple of cars but it really had no effect. It is possible to do it on your car but the location of the ECM makes it complicated.

It is in the right wheelhouse behind the front tire. You have to remove the shield to access the connections and even then it can be a pain because it is rather tight in there. How many times have you seen the message since you have been in last?

As you can read yourself, it's frustrating to know there are other error readings that could have, but weren't checked. There also is a bulletin describing the cleaning suggested here, but that wasn't found until I wrote him about it. By the way i read through the Service manual last night and when I finally got to page 899, it clearly stated that the SVS message is set by the ECM. sounds like the BCM is easily access and cleaned, but now I'm not sure that's the problems, but worth a try.

I'll keep you all posted. :skep

I like your technician!! He is both communicating and sincerely trying to resolve your problem.

I am on real good terms with my dealer techs that worked on my 2004 XLR and now my 2008 "V". I will try and describe your issue to them as well and see what they can turn up.

Regards

Thanks for the encouragement and any help is appreciated. As was previously mentioned, it's hard to believe this is the first time this issue has appeared, hopefully some other tech out there has seen the same thing.

email#1

"I can see them using the SVS message on an early failure of a PCM/ECM code,

I don't understand this. My 2004 w/s manual is 100% transparently clear on the meaning of this message. It means 'non-emissions related problem' and it is raised by the ECM. This is not an 'early failure of the ECM' message (though that could be the root cause). Later on (in this thread) there is a note re legal wording, which is true as far as it goes. However, that misses the point that a non-emissions related fault (and there are many) must NOT light the MIL (SES) lamp. This means that the ECM has to use a different message. Sometimes it is a lamp (a red circle with a ! in it is used by some), the XLR uses the SVS message.


however they are required by ANSI to store freeze frame/fail record data when any code sets. I am not sure if we checked for ff/fr data even though the computer said no codes. we might try that next time you come by.


And then again, maybe not. If you have a power glitch in the ECM it could easily erase all the ff data too. Anyway, what will it prove if there is any?


On most cars the SVS message is reserved for body functions,


But not the 2004 XLR. It is 100% reserved for the ECM.

but like I said before engineers kind of do whatever they want since there are no laws around the use of this indicator/message. Please keep reminding me to do some research and feel free to stop by and I'll check the codes and freeze frames again.


See notes about legal meaning of SES lamp above. Also, it took me about 3 minutes to look up the meaning of the SVS message, and I am using a paper copy of the w/s manual.

email #2

There is a bulletin on some cars for certain issues to remove the connections, make sure they are clean and apply some dielectric grease. I have done it on a couple of cars but it really had no effect. It is possible to do it on your car but the location of the ECM makes it complicated.

It is in the right wheelhouse behind the front tire. You have to remove the shield to access the connections and even then it can be a pain because it is rather tight in there. How many times have you seen the message since you have been in last?

As you can read yourself, it's frustrating to know there are other error readings that could have, but weren't checked. There also is a bulletin describing the cleaning suggested here, but that wasn't found until I wrote him about it. By the way i read through the Service manual last night and when I finally got to page 899, it clearly stated that the SVS message is set by the ECM. sounds like the BCM is easily access and cleaned, but now I'm not sure that's the problems, but worth a try.

I'll keep you all posted. :skep

Well, the good news is your service tech is talking to you. The bad news seems to be a reluctance to get down and do what needs doing, which is the look very closely at the ECM and the power supply (which includes the grounds!!!) to the ECM. You are just going to have to do this, that is, get this done.

Now on another point, I was looking at my XLR and remembered this thread, so I thought I would check that all the fuses and relays in the underhood relay center are firm. You know what? Every single one of them snugged down when I pressed it, maybe only a 1/64 of an inch for some, but for one relay it had nearly fallen right out. So, easy job for you. Lift the cover on the fuse center and check all the fuses are firm. In 2004 fuse 11 is the ECM's constant power supply.

Look on the bright side, this problem with your XLR is going to be fixed!

I tend to agree. I purchased a copy of the 2005 XLR Service Manuals a while back. I dug them out and started looking, not very easy to dig through. Of course BCM or SVS message are no where to be found in the index. After some searching, page 899 of the manual says basically the same thing your 2004 does. the SVS is set by the ECM for a non-emissins relate engine problem. Thus my logic says the SVS message on, the ECM told it so and should know why. No codes in ECM may mean ECM problem, its a computer after all and could have a "glitch" as they say. On the flip side, I was told the XLR systems are redundant, if a code is received in the ECM there is a redundant code stored is the sending module (BCM, TCM, VCIM). All other modules had no code, once again pointed towards the ECM acting rogue. Conclusion, problem with ECM or untraceable electrical issue to the ECM...

I tend to agree. I purchased a copy of the 2005 XLR Service Manuals a while back. I dug them out and started looking, not very easy to dig through. Of course BCM or SVS message are no where to be found in the index. After some searching, page 899 of the manual says basically the same thing your 2004 does. the SVS is set by the ECM for a non-emissins relate engine problem. Thus my logic says the SVS message on, the ECM told it so and should know why. No codes in ECM may mean ECM problem, its a computer after all and could have a "glitch" as they say. On the flip side, I was told the XLR systems are redundant, if a code is received in the ECM there is a redundant code stored is the sending module (BCM, TCM, VCIM). All other modules had no code, once again pointed towards the ECM acting rogue. Conclusion, problem with ECM or untraceable electrical issue to the ECM...

Get a new ECM fitted as a trial, by the sound of it the labor to get to it makes cleaning the connections a small part of the cost.

BTW, I looked up "Driver Information Center Description and Operation" in the index and it took me to 8-398 and 8-399, which is where a bunch of messages are described, including the SVS message.

All the best!

Car is back in the shop. Still getting intermittent SVS message in the DIC, but no error codes in any of the computers, none of the history, nowhere.

After raising a stink with the Director of Service, there was miraculous contact made with GM engineers, including the guy (Chris I think?) who was responsible for the XLR line when it was in production. They are running some tests he suggested, and he is on his way to Atlanta where he says he will see and discuss the problem with one of the best XLR techs he worked with. So I am in waiting mode until tomorrow.

Here's the interesting part. He agrees with my local tech that it is a body problem being processed by the BCM or a problem with the BCM. They all agreed that the GM Service manual and other documentation is wrong. The BCM is solely responsible and sets the Service Vehicle Soon message. The ECM sets and controls the Service Engine Soon and Engine light. Who am I to argue?

I'll keep you ll posted. Oh yeah, they said if these tests or worst case replacing the BCM doesn't work, they're at a loss :skep

Car is back in the shop. Still getting intermittent SVS message in the DIC, but no error codes in any of the computers, none of the history, nowhere.

After raising a stink with the Director of Service, there was miraculous contact made with GM engineers, including the guy (Chris I think?) who was responsible for the XLR line when it was in production. They are running some tests he suggested, and he is on his way to Atlanta where he says he will see and discuss the problem with one of the best XLR techs he worked with. So I am in waiting mode until tomorrow.

Here's the interesting part. He agrees with my local tech that it is a body problem being processed by the BCM or a problem with the BCM. They all agreed that the GM Service manual and other documentation is wrong. The BCM is solely responsible and sets the Service Vehicle Soon message. The ECM sets and controls the Service Engine Soon and Engine light. Who am I to argue?

I'll keep you ll posted. Oh yeah, they said if these tests or worst case replacing the BCM doesn't work, they're at a loss :skep

I find it difficult to believe the BCM is NOT controled/overshadowed by the ECM. The 'GMLAN" system works off of a very simple 'kingdom system', that has basic rules like a chess game. I (IMHO) feel that IF the BCM did report a body fault to the ECM and it was not athenticated (handshake) the ECM would overrule and log a fault. (sticky) There would be a "DIC report" and a fault in the ECM history. At this time the BCM may or may not know that it made an error. Kavassor CAN Kingdom system. CAN = controled area network. Choose one, BCM or ECM, there can only be ONE KING in any kingdom. I feel GM chose engine function (limp home mode) over body functions. You can 'pull a cable' if the body electrical fails and you will be able to open the door. What ' safety cable' is provided to prevent 'walking home' ? The all mighty ECM.

Car is back in the shop. Still getting intermittent SVS message in the DIC, but no error codes in any of the computers, none of the history, nowhere.

After raising a stink with the Director of Service, there was miraculous contact made with GM engineers, including the guy (Chris I think?) who was responsible for the XLR line when it was in production. They are running some tests he suggested, and he is on his way to Atlanta where he says he will see and discuss the problem with one of the best XLR techs he worked with. So I am in waiting mode until tomorrow.

Here's the interesting part. He agrees with my local tech that it is a body problem being processed by the BCM or a problem with the BCM. They all agreed that the GM Service manual and other documentation is wrong. The BCM is solely responsible and sets the Service Vehicle Soon message. The ECM sets and controls the Service Engine Soon and Engine light. Who am I to argue?

I'll keep you ll posted. Oh yeah, they said if these tests or worst case replacing the BCM doesn't work, they're at a loss :skep

There are two options here:

1/ They are right

2/ They are wrong (and the service manual is right).

These cars were designed some time ago and memories are not perfect. There is no 'Service Engine Soon' DIC message (according to the 2004 w/s manual (and also assuming I have not missed it - always possible!)). I do agree that the 'Service Vehicle Soon' message sounds like a BCM type message, but weirdness never stopped software developers before now.

I can theorise a bunch of reasons why the Service Engine Soon message is missing, could be a programming error even, though the problem you are describing fits the ECM at least as well as the BCM (or a faulty IPC of course).

If they are as good as they say they are, they will fix it. The idea that they might run out of ideas is absurd.

Hello majik755

Have you any update to this problem?

Anyhow, I stumbled across a description of a problem that is similar to yours in that it doesn't set a code, but otherwise it is different:

*****************

No Crank, PRNDL Inoperative
Owners of some 2005 Chevrolet Corvettes and 2004 - 05 Cadillac XLRs may experience a no-crank condition, with no codes in any module. The concern may be followed by an inoperative transmission range indicator (PRNDL). The Tech 2 will show the transmission range circuits are all reading high when any gear is selected.

Check for a loose or broken ground G402 at the right rear suspension cradle. See SI document 1495107.

*****************

Not sure how helpful this can be, but it does highlight a means to have a fault without a fault code.

You are sure that this problem is from within the ECM or BCM ? No small 'split second event' anywhere thruout the 'can network' could effect the ECM in this way ? I'm finding it hard to understand how a BCM internal problem would not 'throw any codes' when the ECM is still operating the car/motor in normal fashion. First of all, it happens "at start up", I read nothing about any other operational activity. Second, the "Service Engine Soon" warning is directed to 'engine only questions' and not 'body' or 'accessory' related. The ECM (as I have quickly read on line) is the 'king' of this vehicle's 'domain' and has 'rule' over the BCM. (right ?) This means that IF the BCM WANTED to DO ANYTHING, the ECM would be required to allow the BCM to do that action. The ECM sends a signal to the BCM, put the "SES lamp" on. The BCM reads that signal, sends a reply 'yes I put on the "SES lamp" (in English or other) right now. The ECM would reply 'OK' handshake. "Signal sent, reply/action, handshake". IF the BCM (were malfunctioning) sent/action "SES lamp", the lamp would come on, the reply back to the ECM would be sent at the same time and the ECM would NOT OK HANDSHAKE, it would throw a code. Because the ECM didn't send any signal for any action/reply to the BCM. IMHO, the ECM can and will operate without the BCM functions operational, but the BCM cannot function without the ECM. Correct ? I offered the above insite because I know that the "GM and Mercury Marine" can systems are almost identical in structure and software. GM designed both/all of these systems. Along with the fact that I have found this problem in the Mercury Marine DTS systems. (fly by wire) It's a long story, but it did take over 75 hours of testing (3 months) of "one change/test" at a time.

I'm very happy to know that someone around here has a factory manual and is able to read it! IMHO the ECM MUST OK all messages/functions or the ECM is at fault. Also, IMHO vehicle movement and control are priority over all 'body and accessory modules'. So the ECM is the KING of the kingdom.

I do not know if you ever solved the problem but I know the solution to your problem if you do still have the car or if they ever fixed it. Msg back here and I will tell you what to do.

Car is back in the shop. Still getting intermittent SVS message in the DIC, but no error codes in any of the computers, none of the history, nowhere.

After raising a stink with the Director of Service, there was miraculous contact made with GM engineers, including the guy (Chris I think?) who was responsible for the XLR line when it was in production. They are running some tests he suggested, and he is on his way to Atlanta where he says he will see and discuss the problem with one of the best XLR techs he worked with. So I am in waiting mode until tomorrow.

Here's the interesting part. He agrees with my local tech that it is a body problem being processed by the BCM or a problem with the BCM. They all agreed that the GM Service manual and other documentation is wrong. The BCM is solely responsible and sets the Service Vehicle Soon message. The ECM sets and controls the Service Engine Soon and Engine light. Who am I to argue?

I'll keep you ll posted. Oh yeah, they said if these tests or worst case replacing the BCM doesn't work, they're at a loss :skep

I do not know if you ever solved the problem but I know the solution to your problem if you do still have the car or if they ever fixed it. Msg back here and I will tell you what to do.

Well, I'm all agog, what is the solution?

From his post on the other forum, he recommends disconnecting the transmission solenoid to bypass the safety interlock due to the cost of the new part (~$180.)

Peace of mind . . . priceless.

CC :nono