Help! Service Vehicle Soon Message

[majik755]

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.

Originally Posted by majik755

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 had this problem and they replaced the PCM what ever that is and havent had the problem since. Maybe Cadillac tech can provide more info.

Fred

[majik755]

Fred,

Thanks for your update. I hope Cadillac tech or someone else may have seen this as well. May I ask where you service your car, maybe my tech can call and get information from the guys over there. The problem right now is, the warranty will not replace a part without some direct indication (a code) that it is bad. My guy said he suspects the BCM (Body Control Module) but without a code can't confirm it so it's a shot in the dark, though this module has had other problems in the past. Not sure what a PCM is either but I know there are multiple other computers throughout the car as well.

Originally Posted by majik755

Fred,

Thanks for your update. I hope Cadillac tech or someone else may have seen this as well. May I ask where you service your car, maybe my tech can call and get information from the guys over there. The problem right now is, the warranty will not replace a part without some direct indication (a code) that it is bad. My guy said he suspects the BCM (Body Control Module) but without a code can't confirm it so it's a shot in the dark, though this module has had other problems in the past. Not sure what a PCM is either but I know there are multiple other computers throughout the car as well.

My engine light went on but would not give a code also this was a constant thing and I have a certified warranty which they have to give me a vehical when ever I bring it in and this got costly and also a pain in the butt for me to go through. My dealor is Don Mackey Cadillac however, he lost his dealorship and was given it back but was restricted to selling Cadillac only so he got disgusted and then he sold it to Royal Group Tucson Buick Cadillac GMC. I know they had a hugh rollover of employees the entire dealorship was re-organized from top to bottom but you can have them try. Their phone number is 520-624-0481.

Fred

[majik755]

Thanks for the info, I can at least pass it on to the tech here hopefully he can find out something that way. Maybe someone else out there has a similar experience as well, or one of our techies has an idea.

[ccclarke]

XLR doesn't have a PCM. BCM is definately a good first candidate to suspect, but intermittent glitches, --like timing errors that trigger error messages without no codes, are very hard to pin down unless spare modules are available to swap in/out, which GM discourages.

Complexity is a double-edged sword. XLR's architecture takes a lot of the traditional labor out of the troubleshooting process, but when the normal paths don't apply/work, it takes a detailed level of system knowledge and lots of experience to root out the problem.

In a case like this, it would be helpful to use a logic protocol analyzer to monitor the nodes on each bus to determine which module is setting the flag that creates the message. You would also need firmware documentation to make it all comprehensible. This level of troubleshooting is way beyond what a dealership is capable of, which is why module swapping (what is commonly referred to as Easter-egging) is relatively quick, and if done logically, yields reasonably fast results when traditional methods fail.

It could be something as simple (but often hard to find) as a dirty pin in a connector, or broken strands in a conductor changing the resistance of the bus as well.

Keep us posted!

CC

Originally Posted by ccclarke

XLR doesn't have a PCM. BCM is definately a good first candidate to suspect, but intermittent glitches, --like timing errors that trigger error messages without no codes, are very hard to pin down unless spare modules are available to swap in/out, which GM discourages.

Complexity is a double-edged sword. XLR's architecture takes a lot of the traditional labor out of the troubleshooting process, but when the normal paths don't apply/work, it takes a detailed level of system knowledge and lots of experience to root out the problem.

In a case like this, it would be helpful to use a logic protocol analyzer to monitor the nodes on each bus to determine which module is setting the flag that creates the message. You would also need firmware documentation to make it all comprehensible. This level of troubleshooting is way beyond what a dealership is capable of, which is why module swapping (what is commonly referred to as Easter-egging) is relatively quick, and if done logically, yields reasonably fast results when traditional methods fail.

It could be something as simple (but often hard to find) as a dirty pin in a connector, or broken strands in a conductor changing the resistance of the bus as well.

Keep us posted!

CC

I dont know about the PCM not on a XLR but the notation on the work order/billing states "replaced PCM FP number 12576523 Module 3.670"
I havent had the problem since this was done.

Speedway

[Cadillac Tech]

PCM (powertrain control module) is often used to describe the computer that controls the engine. PCMs are used to control both the engine and transmission in one unit. These were used several years ago when there were fewer modules in a vehicle.

Most vehicles today use multiple modules to operate the different systems. An XLR has an ECM (engine control module) just for operating the engine and a TCM (transmission control module) to control transmission operation. The BCM (body control module) is the busiest module in the vehicle. All of the other modules communicate with the BCM and wait for it's orders. The BCM is the most likely to fail and may be the cause of this problem.

[Cadillac Tech]

Engine Control Module Description
The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The engine control module (ECM) is the control center of this system. The ECM monitors numerous engine and vehicle functions. The ECM constantly monitors information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The ECM also performs diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver via the malfunction indicator lamp (MIL). When the ECM detects a malfunction, the ECM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. Review the components and wiring diagrams in order to determine which systems are controlled by the ECM.
Malfunction Indicator Lamp (MIL) Operation

The malfunction indicator lamp (MIL) is located in the instrument panel cluster. The MIL will display as either SERVICE ENGINE SOON or one of the following symbols when commanded ON:



The MIL indicates that an emissions related fault has occurred and vehicle service is required.
The following is a list of the modes of operation for the MIL:

•	The MIL illuminates when the ignition is turned ON, with the engine OFF. This is a bulb test to ensure the MIL is able to illuminate.

•	The MIL turns OFF after the engine is started if a diagnostic fault is not present.

•

The MIL remains illuminated after the engine is started if the control module detects a fault. A diagnostic trouble code (DTC) is stored any time the control module illuminates the MIL due to an emissions related fault. The MIL turns OFF after three consecutive ignition cycles in which a Test Passed has been reported for the diagnostic test that originally caused the MIL to illuminate.

•	The MIL flashes if the control module detects a misfire condition which could damage the catalytic converter.

•	When the MIL is illuminated and the engine stalls, the MIL will remain illuminated as long as the ignition is ON.

•	When the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition is cycled OFF and then ON.

© 2010 General Motors. All rights reserved.

[majik755]

Thanks all. Sounds like the BCM is the most likely candidate, which is where my mechanic was heading. There is no indicator light showing, just the Service Vehicle Soon message in the DIC, so doesn't sound like ECM is the culprit. Thanks for the explanations Cadillac tech. Problem that exists now is justifying replacement, warranty replacement requires a code or some other justification.

[majik755]

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

[XFireXLR]

I have not experienced this problem (knock on wood), but twice in the last two months while using the Cruise Control and disengaging it to exit the parkway the DIC will chime but there is no message. This will happen while I am exiting the parkway and having one of the turn signals on, once I shut off the turn signal the chime will stop, but still no message in the DIC.

[tonypro99]

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.

Originally Posted by majik755

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

[cubby558]

These posts are almost two years old and it doesn't look like he ever responded back if it was fixed or not, but I would assume either he gave up or had it fixed and just didn't respond back.

I'm wondering though why you posted, stating to have the solution, but want to PM, rather than share your information with the forum. That's what this is for.

Originally Posted by tonypro99

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.

[tonypro99]

Cubby I never said anywhere "PM" me back??? I said msg me back here and I will tell you the fix meaning replying back to the forum.