C1291

DTC C1291





Test 1-4





Test 5-14

Circuit Description
The stop lamp switch signal informs the EBCM when the brake pedal is pressed.

Conditions for Running the DTC
The ABS conditions and the braking conditions are normal.

Conditions for Setting the DTC
^ The stop lamp switch remains open for 3 deceleration cycles.
^ A DTC C1291 was set in a previous ignition cycle.

Action Taken When the DTC Sets
^ The EBCM disables the TCS for the duration of the ignition cycle.
^ The Traction Off indicator turns ON.
^ The ABS remains functional.

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present and you used the scan tool Clear DTC function.
^ The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
^ Diagnose any wheel speed sensor DTCs before continuing with the diagnosis of the DTC.
^ A deceleration cycle consists of the following sequence:
1. The vehicle speed is greater than 24 km/h (15 mph).
2. The vehicle decelerates more than 8 km/h/second (5 mph/second) for 2 seconds.
3. The vehicle speed decelerates to less than 16 km/h (10 mph).
^ Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch on within 2.54 cm (1 inch) of travel.
^ Possible causes of this DTC are the following conditions:
- An open stop lamp switch
- The stop lamp switch is misadjusted
- An open fuse
- Circuit has a wiring problem, terminal corrosion, or poor connections
- Erratic wheel speeds

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. Tests the circuit for a change in states.
5. Tests for proper operation of the circuit by bypassing the stop lamp switch. If the fuse in the jumper opens when you perform this test, the signal circuit of the stop lamp switch is shorted to ground.