C1277

Circuit Description
Traction Control is simultaneously controlled by the EBCM and the Powertrain Control Module (PCM). The PCM receives a REQUESTED TORQUE request via a Pulse Width Modulated (PWM) signal from the EBCM requesting the desired torque level for proper Traction Control system operation. The PCM supplies the pull up voltage.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
DTC C1277 can be set when there is an open or short in the Requested Torque line between the EBCM and PCM or there is a TCS communication malfunction detected by the PCM and indicated to the EBCM, by broadcasting a Class 2 message.

Action Taken When the DTC Sets
^ TCS is disabled.
^ Traction Control (TRAC OFF) indicator is turned on.
^ Service Vehicle Soon Indicator is turned on.
^ ABS remains functional.

Conditions for Clearing the DTC
Condition for DTC is no longer present and scan tool is used to clear the history DTC.

Diagnostic Aids
^ Possible causes for DTC C1277 to set are:
- Requested Torque line open.
- Requested Torque line shorted to ground.
- Requested Torque line shorted to voltage.
- Communication frequency malfunction.
- PCM not receiving Class 2 message.

^ 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.
^ If an intermittent malfunction exists refer to Testing for Intermittent and Poor Connections.