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Hi,

Thommy in Sweden need your help!

I have a Cadillac STS, 2001. Have problems with warning lights (Brake,ABS and TC) come on every now and then for no particular reason.

When the warning lights are on, the the air condition is not working properly and the parking brake will not come loose. No problem when the warning lights are off.

Have tried to "clear all codes" on the dashboard. This works sometimes, but usually not. Often the system refuses to clear the codes.

The following codes are current:

IPC 1000

PCM P1571

PCM P1644

PCM U1040

RSS C0635

RSS C0615

RSS C0640

RSS C0710

SDM U1040

Have checked the earth connections and connections on each wheel. Have been informed that it might be the EBCM that needs to be replaced, but does this also affect the air condition and TC!?

Please, I need your help!

Best regards,

Thommy Sweden

Edited by Thommy Sweden
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The RSS codes are the cause of the ABS/Traction Control warning lights.

I don't have a 2001 shop manual but take a look at this thread - it may help out:

http://www.cadillacforums.com/forums/cadillac-forum/t-36211.html

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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IPC
U0001 Controller Area Network (CAN) Bus Communication (ECM)

PCM
P1571 Traction Control Torque Request Circuit
P1644 Traction Control Delivered Torque Output Circuit
U1040 Loss of Class 2 Communications with ABS

RSS
C0635 Left Front Normal Force Circuit Malfunction
C0615 Left Front Position Sensor Malfunction
C0640 Right Front Normal Force Circuit Malfunction
C0710 Steering Position Signal Malfunction

SDM
U1040 Loss of Class 2 Communications with ABS

With these codes, your ABS and TC lights will be on if they are CURRENT. Please make a note of which ones are CURRENT.

I have a 2002 FSM on DVD and I think it will apply to your car here. I would start by looking at the left front position sensor and making sure it is OK, the connector is clean and tight, and the wires to it are OK. If you can find it, do the same for the steering position sensor. Post back which codes are CURRENT and we will get it from there.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The three PCM codes say that the PCM could not talk to the EBTCM through either the network or the dedicated torque request lines that are used in traction control. If any of them are current, you will get warning lights for traction control and/or ABS, and possibly DIC messages about stability, "speed limited to..." etc.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Yesterday I went to the local workshop and they checked the left front sensor and other connectors around all 4 wheels. As far as they understand everything look perfectly ok. All codes was cleared and my Cadillac worked perfect for nearly 2 days!

Tonight when I started the car so was all the warning lights back, ABS, Brake and TC.

Following codes are CURRENT:

IPC U1000

PCM P1571

PCM P1644

PCM U1040

RSS C0635

RSS C0640

RSS C0710

SDM U1040

Looking forward to hear from you.

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IPC U1000
U1000 Class 2 Communication Malfunction

PCM P1571
P1571 Traction Control Torque Request Circuit

PCM P1644
P1644 Traction Control Delivered Torque Output Circuit

PCM U1040
U1040 Loss of Class 2 Communications with ABS

RSS C0635
C0635 Left Front Normal Force Circuit Malfunction

RSS C0640
C0640 Right Front Normal Force Circuit Malfunction

RSS C0710
C0710 Steering Position Signal Malfunction

SDM U1040
U1040 Loss of Class 2 Communications with ABS

Your EBTCM is down. I would start with

  • The 10 Amp ABS fuse in the rear fuse block.
  • The 50 Amp Maxifuse in the underhood fuse block
  • Loose, dirty, or damaged EBCM connector.
  • Bad or missing ground from the rear of the ABS motor.

From the 2002 FSM section on P1571, the things to look for before bringing out the code reader and such are:

  • An open in the requested torque circuit
  • An short to ground or voltage in the requested torque circuit
  • A wiring problem, terminal corrosion, or poor connection in the requested torque circuit
  • A communication frequency problem
  • A communication duty cycle problem
  • The PCM is not receiving information from the EBCM
  • Loose or corroded EBCM ground or PCM ground

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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As you have already understand, I am not an engineer, only user of my Cadillac..... EBTCM and EBCM is the same module and sitting in front of the left front wheel at my STS 2001 ?

Yes - it is the module in front of the left front wheel and has brake lines hooked to it. The correct term is EBTCM (Electronic Brake and Traction Control Module).

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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They dropped the "T" in the FSM in later models for some reason. EBTCM and EBCM are interchangeable as they are identical in the schematics.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thanks for info, Jim. I have checked and cleaned the fuses myself, but unfortunately it didn't help.

The workshop will check the EBTCM on Monday.

If you or anyone else has further ideas about the cause of my problems, I would appreciate it if you could inform me so that the workshop also can check this.
Guess it's EBTCM problems, as you mention above ..... or maybe that EBTCM should be replaced with a new one!?

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Hej Thommy!

Kolla framför allt det Jim har markerat med rött ovan dvs jordkontakt alltifrån polskor, jordflätor, jordpunkter på karossen till direkt jordning av EBCM. Det räcker inte med att de ser ok ut - de måste demonteras, rengöras och fettas in med t.ex. vitt vaselin innan återmontering.

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Ooopps.... Har tyvärr ingen verkstadshandbok för 2001 så jag vågar inte svara på det. Borde dock vara troligare att felet sitter i/vid EBCM. PCM sitter förmodligen mer skyddat och kanske t.o.m. inne i kupéen.

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The PCM is under the air cleaner. The intake path is a cool air port behind the left headlight, to a port into the engine compartment covered by a large plastic box. The air flows over the PCM cooling fins, then through the air cleaner element, then out the long L-shaped hose to the fuel injection throttle body.

The PCM rarely gives any trouble at all. The EBCM, on the other hand, has a motor and two relays that can wear out. I see nothing in your codes that would lead me to believe that there was any problem with the PCM.

On the other hand, it's clear that the EBCM is failing to perform its functions and also failing to communicate over the car's network. I would not touch the PCM until the EBCM codes were taken care of.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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My Cadillac is back from the workshop and they have carefully checked all connectors, ground and wire conditions. All connectors and ground connectors has be cleaned and checked...as recommended.

Unfortunately I still have the same problems as before and all codes comes back after clearing the codes. Same codes are CURRENT as mentioned earlier.

...so I still need your help to solve this annoying problem with my dear Cadillac.

Look forward to hearing from you shortly. :)

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If all the EBCM codes are CURRENT and the fuses and grounds are good, then the next step is to try a known good EBCM.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Can you recommend a company that can repair the EBCM ? Can't anyone in Sweden....

Or is it recommended to buy a new one!?

Göran W - Do you know where it can be repaired in Sweden?

Tommy Sweden, in case you haven't heard that statement by Cadillac Jim, "known good part", I would highly recommend it. You buy a new or rebuilt and do not KNOW it is in working condition. That is the reason a shop will keep a known good part around for diagnosis. Then replace with new etc..

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