C1277

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Part 2 Of 2:

CIRCUIT DESCRIPTION
The Electronic Brake and Traction Control Module (EBTCM) and the Powertrain Control Module (PCM) simultaneously controlled the traction control. The PCM sends a Requested Torque message via a pulse width modulated (PWM) signal to the EBTCM requesting the desired torque level for proper Traction Control System (TCS) operation. The EBTCM 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 EBTCM and the PCM.
^ A TCS communication malfunction detected by the PCM and indicated to the EBTCM via a PWM message.

ACTION TAKEN WHEN THE DTC SETS
^ A malfunction Diagnostic Trouble Code (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
^ 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 Diagrams..
^ The following conditions can cause this concern:
- An open circuit.
- An short to ground or voltage in the circuit.
- A wiring problem, terminal corrosion, or poor connection in the circuit.
- A communication frequency problem.
- A communication duty cycle problem.
- The EBTCM is not receiving information from the PCM.


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