C1277

Part 1 Of 2:

Part 2 Of 2:

CIRCUIT DESCRIPTION
The EBCM/EBTCM and the PCM simultaneously control the traction control. The PCM receives a Requested Torque message via a Pulse Width Modulated (PWM) signal from the EBCM/EBTCM requesting the desired torque level for proper TCS operation. The PCM supplies the pull up voltage.

CONDITIONS FOR SETTING THE DTC:
The DTC sets if one of the following occur:
^ An open or short in the Requested Torque line between the EBCM/EBTCM and the PCM.
^ A TCS communication malfunction detected by the PCM and indicated to the EBCM/EBTCM via a PWM message.

ACTION TAKEN WHEN THE DTC SETS
^ A malfunction DTC is stored.
^ The TCS is disabled.
^ The TRACTION OFF 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
^ It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
^ An intermittent malfunction can be caused by poor connections, 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 Information and Procedures.
^ The following conditions can cause this concern:
- An open in the Requested Torque circuit.
- An short to ground or voltage in the Requested Torque circuit.
- A wiring problem, terminal corrosion, or poor connection in the Requested Torque circuit.
- A communication frequency problem.
- A communication duty cycle problem.
- The EBCM/EBTCM is not receiving information from the PCM.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
4. This step checks for the proper duty cycle.
5. This step checks for the proper frequency.