1998 Cadillac El Dorado "Service Stability System"

1998 CADILLAC ELDORADO
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BOB HUNLEY
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Computer problem
1998 Cadillac El Dorado V8 Front Wheel Drive Automatic

"Service Stability System" alert appears on DIC. Simultaneously a weird undercarriage noise is heard. Appears to be coming from the left front of the vehicle.
Also simultaneously the brakes seem to operate momentarily, then releases. Steering also seems to be affected momentarily.

The dealer says the codes indicate two problems: (1) Steering Wheel Centering, and (2) Defective Stability System Module.... ($1,300 for parts, minimum $500 labor.

I am not a mechanic, but this diagnosis seems to contradict logic. Logic tells me that the module is simply identifying a mechanical problem, not causing it.
Dec 10, 2009 at 10:52 PM
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FACTORYJACK
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Without code numbers, I don't know what makes the module defective. The steering fault is probably a c1287, and is common. I would clear the codes and see what returns. The noise associated with the service message could be inadvertent ABS activation. There is a bulletin for that:

#PIC3300: ABS Light On DTC C1226 or Unwanted ABS or TCS Activation 1996 - 2000 Eldorado 1997 Seville 1997 - 1999 Deville - kw brake accelerate - (Dec 15, 2004)


Subject: ABS Light On DTC C1226 or Unwanted ABS or TCS Activation 1996 - 2000 Eldorado 1997 Seville 1997 - 1999 Deville


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The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:
ABS lamp on with a DTC C1226 and/or unwanted TCS or ABS activation may be caused by Electromagnetic Interference (EMI) in the right front wheel speed sensor harness induced from the rear bank of the secondary ignition wires.

Recommendation/Instructions:
Correct any concerns which exist with the secondary ignition wires or spark plugs. If no secondary ignition concerns are evident, inspect the harness routing of the secondary ignition wires. Shielding the harness on the right side has not been consistently successful. The technician should restring the wheel speed circuits from the EBTCM to the wheel speed sensor jumper harness connector on the right front side. A shielded harness part number 12140077 can be used on the right side. Install two twisted pair (Part #12140077) harnesses soldered together at the non-connector end to make one harness. Route the harness down the right frame rail, under the core support to the EBTCM.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

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Models:
(1996-2000 Cadillac Eldorado) and (1996-2000 Cadillac Eldorado ETC) and (1997 Cadillac Seville SLS 1997 Cadillac Seville STS) (1997-1999 Cadillac Deville 1997-1999 Cadillac Deville De'Elegance 1997-1999 Cadillac Deville Concours)
Dec 11, 2009 at 10:36 PM