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2005 CTS
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5 Posts
Discussion Starter #1
First let me apologize, I know there are several posts and threads about this very issue, but I need help.

I have a 2005 CTS 3.6L, auto trans with 120,000 miles on it. During the bad weather we had here in the Boston area over the winter, I didn't drive my CTS for two months. When I did go to start it after it sat I jump started it and let it idle, but the transmission cooler line broke off the radiator before I could get out of the parking spot. I had it towed to my work (I am a BMW/MINI technician) and I put a new radiator in it and refilled the transmission with fluid, bled the cooling system, etc. All was well after that repair, I pulled the car out of my shop and parked it outside and left it for a day (as I had been driving my truck to and from work while the car was down). The next day, I went to take my CTS to lunch as a test drive, and it would not crank, would not start. Key was stuck in ignition, couldn't turn it to the "position 0". DIC display showed "Service Security System" or something along those lines. I manually released the key, tried my other key I have for the car, still same issue.

I immediately searched this forum and found several threads about people having similar issues. After enough reading, I determined that most people find the Theft Deterrent Module to be the culprit, or the ECM itself. I think I also found one where the body control module was causing the issue.

I ordered the TDM as it was the cheaper part compared to needing an ECM. Once it arrived I installed it, along with a new battery (as the previous battery was on its last leg due to the car sitting for so long). After replacing the TDM, I attempted to do the PATS III key relearn, but had an issue. When I put a key in to start the 10 minutes on, off, 10 minutes on, off, 10 minutes on procedure, the security light would turn on and then go out almost immediately, and after 10 minutes the key would still not turn to "position 0". I jumped the pins of the starter relay with the key on, and the engine starts. After doing that, I COULD take the key out, and I was able to perform the 30 minute key relearn process.

Once the keys were relearned, the car starts! I was relieved, and thought my ordeal was over. Nope. Now that the keys are relearned, I was able to start the car, and as a test, I pulled the key out and immediately tried starting the car, and it WOULD start. I found that as long as I tried starting it rather quickly after turning the car off, the car would start as normal. HOWEVER, if I take the key out and allow the vehicle to sit for ten minutes, the issue returns. The car will not crank or start, the key cannot be released from the ignition without the manual release.

I was able to jump the relay again and start the engine. And after doing that, the keys will work normally to start the car, again for only a few minutes. Once the car sits, the issue pops up again.

With a hand held scanner, I found fault code U0100 stored for communication. I cleared the fault once I got the car to start in that 10 minute window, and test drove the vehicle. While driving the vehicle on a test drive, I scanned for codes and the fault does not return while the engine is running. Even after parking after the test drive the fault does not return on rescans. However, once I let the vehicle sit for that 10 minutes and find that I can't start it, a rescan shows the U0100 fault setting. I also have found fault U1000 to store, however that was before I replaced the TDM and relearned the keys.

I tried cleaning the ECM connectors under the hood with electrical connector cleaner, and applied dielectric grease, with no change in condition.

Thank you for reading, I know it was long and I know there is tons of info/threads floating around about this issue. I was just hoping someone would read everything I've done and be able to advise me on what to do next based on their personal experience. It seems the next step is to replace the ECM, which I know can be expensive. I don't want to bring the vehicle to a dealership. Where can I get a quality ECM online that will come programmed for my vehicle? How much am I looking at for cost? Also, is there anything else I should look into before ordering an ECM and potentially wasting my money?
 

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Registered
2005 CTS
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5 Posts
Discussion Starter #2
BUMP...

I messed around with the car for a few days, still intermittent issues with starting. I walked out to the car Friday afternoon after it sat for two days, and it started right up. Using a Snap On Solus scan tool that my dealership uses for our used cars and trade ins, I went through every individual module and cleared out faults. Then Saturday morning (today) I went to start the car, no crank no start, key locked in ignition, and the PRND32 next to the shifter were not lit up. I noted that when I initially put the key to the on position, the check engine light did not illuminate. My shop foreman is a former GM tech, and he said that when you turn the key on and the check engine light doesn't come on, that means that the ECM is not communicating.

I scanned the car in this above described condition with the Solus, and the ECM could not be scanned (the key was on). I scanned the TCM, and fault U0100 was stored for Lost Communication with ECM/PCM. I scanned the Theft Deterrent Module, and fault U1000 was stored in that module. At this point I removed the starter relay under the hood and jumped the pins to get the car to start. Once the car was started, I was able to remove the key without manual release. As I described in the original post, the car could now be started with the key as if all was well, however the check engine light was on, as well as the traction control light. Using the Solus, I was able to scan the ECM this time, and P0700 was stored for transmission control system fault. I also scanned the ABS module since the traction control light was on. There were not current faults present, but in history there were four faults stored. C0243 for Engien Drag Control Manlfunction, C0244 for Pulse Width Modulation Delivered Torque, U1016 for Loss of Class 2 Communication with VCM/PCM, and U1000 for Class 2 Serial Communcation Problem.

I feel since the communication faults can be cleared immediately after they set, and the vehicle can be started by jumping the starter relay (which essentially is forcing the PCM to communicate) it has to be a faulty module. Mostly likely the PCM it seems? Can anyone argue for possibly the body module causing the issue?

If I do indeed need to replace the PCM, where can I get one online that will already be coded? I don't want to install one uncoded and have to bring it to a Cadillac dealer to have it coded. I know how annoyed I get by our MINI customer's coming in and "thinking" the know what their talking about and how they know how to diagnose their car. I'd hate to be "that guy" walking into one of the Cadillac dealers around here.

If it were the Body Control Module (am I correct in thinking that this particular module is mounted on top of the plastic trim panel that is under the glove box, above where the front passengers feet would be?) would that need to be coded to my VIN? And if so, where can i get one of those?
 

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Eldorado
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17 Posts
PhilJL05 : I know this is a old post, however, I have the same identical issues you were having. The only way to release the key was to jump the starter relay. The same lights would come on T/C, check security system,ect. , everything you were experiencing. I connected a push button wired to the starter relay and now turn the key on and use the start button to start the car. It works just fine , also I only use the car once in awhile and a 2004 does not warrant spending the money to have it repaired properly.
Will using the car in this fashion harm anything ? Thank you or anyone who can answer this question in advance.
 
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