C1291

DTC C1291 Open Brake Lamp Switch Contacts During Deceleration






Circuit Description

This circuit detects an open stoplamp/BTSI switch in the non-ABS mode. The EBTCM looks for a deceleration rate that indicates braking action and requires several repeats of this detection method in order to verify this assumption. In each case, the TCS will not be available since the EBTCM detects no stoplamp/BTSI switch voltage.

Conditions for Setting the DTC

The stoplamp switch remains open for 3 deceleration cycles.

Action Taken When the DTC Sets

- A malfunction DTC is stored.
- The TCS is disabled.
- The TRACTION CONTROL indicator is turned ON.
- The ABS remains functional.

Conditions for Clearing the DTC

- The condition for DTC is no longer present and you used scan tool Clear DTCs function.
- The condition for DTC is no longer present and you used the On-Board Clear DTCs function.
- The EBTCM does not detect the DTC in 50 drive cycles.

Diagnostic Aids

- Thoroughly inspect the wiring and the connectors. Failure to carefully and fully inspect the wiring and the connectors can result in misdiagnosis. Misdiagnosis may cause replacement of parts without repairing the malfunction.
- If any WSS DTCs are present, diagnose the WSS DTCs first.
- The following conditions may cause most intermittent malfunctions:
- Poor connections.
- Rubbed through wire insulation.
- A broken wire inside the insulation.
- The following conditions are other possible causes for this malfunction:
- An open stoplamp/BTSI switch.
- An open brake fuse.
- A misadjusted stoplamp/BTSI switch.
- Erratic wheel speeds.
- A wiring problem, terminal corrosion, or a poor connection in the circuit.
- If an intermittent malfunction exists, refer to Intermittents and Poor Connections.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

3. This step tests if the stoplamp switch and power distribution are OK.
4. This step tests for voltage at the EBTCM.
10. This step tests the stoplamp switch.