C1291

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Part 2 Of 2:

CIRCUIT DESCRIPTION
This circuit detects an open stoplamp/BTSI switch in the non-ABS mode. The EBCM/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 EBCM/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 the DTC is no longer present and you used the scan tool Clear DTC function.
^ The EBCM/EBTCM does not detect the DTC in 50 drive cycles.

DIAGNOSTIC AIDS
^ If any wheel speed sensor DTCs are present, diagnose the current wheel speed sensor DTC first. Refer to DTC List.
^ It is very important that a thorough inspection of the wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
^ An intermittent can be caused by poor connection, broken insulation, or a wire that is broken inside the insulation.
^ If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Diagnostic Aids.
^ 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

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step tests if the stoplamp switch and the power distribution are OK
4. This step tests for voltage at the EBCM/EBTCM.
10. This step tests the stoplamp switch.