C1291

Circuit Description
The EBCM uses this stoplamp switch circuit for various performance measures within DRP/ABS/TCS/VSES. The EBCM detects an open circuit in non-ABS braking. This DTC sets when the EBCM does not detect closure of the brake switch while the car is decelerating at level that indicates the brakes are applied. Several deceleration events without detection of a closed brake switch are required before this DTC is set.

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

Conditions for Setting the DTC
The stoplamp switch remains open for 3 deceleration cycles.

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

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
^ The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics 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 stoplamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stoplamp switch on within 1 inch of travel.
^ Possible causes of this DTC are the following conditions:
- An open stoplamp switch.
- The stoplamp 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 stoplamp/automatic transmission shift lock control switch. If the fuse in the jumper opens when you perform this test, the signal circuit of the stoplamp/automatic transmission shift lock control switch is shorted to ground.