C1291

CIRCUIT DESCRIPTION
This circuit is used to detect an open Stoplamp/BTSI switch in the non-ABS mode. The Electronic Brake and Traction Control Module (EBTCM) looks for a deceleration rate that would indicate braking action and requires several repeats of this detection method in order to verify this assumption. In each case, the Traction Control System (TCS) will not be available since the EBTCM sees no Stoplamp/BTSI switch voltage.

CONDITIONS FOR SETTING THE DTC
The Stoplamp/BTSI switch remains open for three deceleration cycles.

ACTION TAKEN WHEN THE DTC SETS
^ A DTC C1291 is stored
^ The TCS is disabled
^ The TRACTION OFF indicator turns on
^ The ABS remains functional

CONDITIONS FOR CLEARING THE DTC
^ The condition for the Diagnostic Trouble Code (DTC) is no longer present and the scan tool clear DTC function is used
^ 50 ignition cycles have passed with no DTCs detected

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 Wheel Speed Sensor (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 Troubleshooting Procedures.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step checks if the Stoplamp Switch and Power Distribution are OK.
4. This step checks for voltage at the EBTCM.
10. This step checks the Stoplamp Switch.