GM Service Manual Online
For 1990-2009 cars only

Object Number: 247754  Size: MF
ABS Components
Antilock Brake System Schematics
Handling Electrostatic Discharge Sensitive Parts Notice
OBDII Symbol Description Notice
Power Distribution Schematics
Exterior Lights Schematics

Circuit Description

DTC C1292 is the second portion of DTC C1291 for DTC C1293. If DTC 1291 or DTC 1292 failed during the last ignition cycle, DTC C1293 becomes a current failure during the next ignition cycle. DTC C1293 failure keeps ABS/ETS disabled until identifying a brake switch on state. When identifying a change during an ignition sycle in which DTC C1293 is a current malfunction, DTC C1291 or DTC 1292 will clear itself at the end of the current igntion cycle. ABS/ETS will then enable itself at the start of the next ignition cycle. DTC C1293 alone indicates DCT C1291 or DTC C1292 failed previously, but is intermittent, or has been corrected.

Diagnostic Aids

If the malfunction is not current, use wiggle test on the wiring harness to pinpoint an intermittent malfunction in the motor circuitry or connections. Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:

    • Backed out terminals
    • Improper mating
    • Improperly formed or damaged terminals
    • Poor terminal-to-wiring connections
    • Physical damage to the wiring harness
    • Rubbed-through wire insulation
    • A broken wire inside the insulation

Use the Data List of the Scan Tool verify proper brake switch operation. The Data List should display the brake switch as the brake is applied within 25 mm (1.0 inch) of brake pedal travel.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

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Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Use the scan tool to read the DTCs.

Is DTC C1291 or DTC C1292 set as either a current and/or a history DTC?

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Go to DTC C1291 Open Brake Lamp Switch Contacts During Deceleration or DTC C1292 Open Brake Lamp Switch When ABS Was Required

Go to Step 3

3

  1. Select DTC history on the scan tool.
  2. Verify that the malfunction frequency was infrequent.
  3. Use the scan tool in order to clear the DTCs.

Did DTC C1293 clear?

--

Go to Diagnostic System Check - ABS

Go to Step 4

4

Replace the EBTCM. Refer to Electronic Brake and Traction Control Module Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

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