2001 Cadillac STS ABS light, brake light, tracton control l

Tiny
HUGHWILSON
  • MEMBER
  • 2001 CADILLAC STS
2001 Cadillac STS

Last summer, had tires put on the car, and immediately when I left the tire shop these lights were on the dash. They erased the codes with their scanner it worked well for about 5 minutes. A year later they come on at start up, sometimes not, sometimes go out, sometimes not. Until the abs and brake go off, if they do I have no heated seats, fog lights, defrost up front. Had a command start put in 2wks ago. Took to deal today and they said they couldn't read any error codes until the command start was disconnected, mech disconnected command start and said there were no codes. No lights on when I left dealership. Later in the day all 3 came back on, went to dealer and couldn't get the scanner to read off the car. They now tell me that it might need a new PCM $1300, a place to start! That is why the scanner won't read. If that is not the problem I have to keep it anyway because they can't return to GM once used. I went home and found tons of error codes using the onboard controls on the dash. I'm not in a position to dump $1300 just for them to guess! If I manually erase codes using dash controls everything works fine for a while. I keep thinking it is something to do with the wheel sensor wires. Codes I found were: PCM 1571,1644, U1040, RSS c0635, c0640, c0710, SDM u1040, IPC u1040, u1000 ABS 1277. I hopes these help
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Monday, December 21st, 2009 AT 7:09 PM

4 Replies

Tiny
FACTORYJACK
  • EXPERT
Unfortunately, you don't have a simple, straight forward concern. I don't see a fault with the wheel sensor wires causing this concern, and there are a few players in the game that could be at fault. One similarity, is they all somewhat relate to the EBCM(brake control module). The P1571 and C1277 are most likely setting together, they are the same, a fault with the requested torque signal that is shared between the PCM and EBCM. The P1644 states the delivered torque signal is invalid. The U1040 codes are loss of communications codes with the brake control module. The C0635 and 640 are faults from the brake controller that set in the RSS module, and the C0710 is set due to an invalid steering position sent from the EBCM and set by the RSS module. With that, I concur with your hesitation on having the PCM replaced. If it were my hip-shot to make, I would lean toward the EBCM. The problem is, it is probably no cheaper. Initially, there are other tests that should be made, like checking EBCM ground integrity. You need someone that is going to make an effort at looking at all the possibilities before just replacing a part. At some point it may come down to needing to replace a module to eliminate the possibility, but that should be made after all avenues have been addressed.
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Monday, December 21st, 2009 AT 11:23 PM
Tiny
HUGHWILSON
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I agree with you, I know what they are going to say"Can't work on the car if we can't get our scanner to talk with your car and that according to them is a new PCM will fix this problem and if it doesn't then at least it is a start" How come I can get codes off the car using the dash controlls and they can't connect to the car using their scanner?
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Tuesday, December 22nd, 2009 AT 7:47 AM
Tiny
FACTORYJACK
  • EXPERT
The PCM is not a gateway for communications on this vehicle, and they should be able to access some module, even if the PCM had no communication. I don't know what is happening, possible the wrong year vehicle is entered during the build. There is a circumstance that communications with no module is achieved, and there is a diagnostic procedure for it. There could also be a problem with the interface cable on the scanner, and no one has discovered it.
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Tuesday, December 22nd, 2009 AT 9:55 PM
Tiny
HUGHWILSON
  • MEMBER
I watched the guy enter the info on the scanner and it was correct. He tried another plug on the end of the scanner with no success. I can still however get error codes off the car using its diagnostics from the dash buttons. Checked in the states and a PCM is 150 plus core vs 1150 up here and the ebcm is 250 in the us vs 1300 up here. These are rebuilts vs new from gm up here. Haven't gone back to the dealer yet, and probably won't. Like doctoring, get a second opinion! Car needs front shocks, will get those fixed and see if that solves some of the problems. Again shocks up here are 1350 each and can get a pair out of arnott in FL for 369 a pair, not electronic, standard shocks, but have the plugins so that the computer is fooled. Not sure I will ever have a cadillac again, nice car just to rich for my blood to own. Another question. If I the heater on floor makes lots of noise but little if any air comes out on the floor. Works great on everything else. No error codes for this, perhaps a new PCM would fix this problem. If I get a PCM can I get it flashed so that the top speed gets changed so it doesn't shut down at 130mph, I have 16" rims, not the 17"?
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Tuesday, December 22nd, 2009 AT 11:07 PM

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