C1276

Circuit Description
The EBCM and the PCM simultaneously control the traction control. The PCM sends a Delivered Torque message via a Pulse Width Modulated (PWM) signal to the EBCM. The duty cycle of the signal is used to determine how much engine torque the PCM is delivering. Normal values are between 10 and 90 percent duty cycle. The signal should be at low values (around 10 percent) at idle and higher values under driving conditions. The EBCM supplies the pull up voltage that the PCM switches to ground to create the signal.

Conditions for Running the DTC
The ignition is ON.

Conditions for Setting the DTC
One of the following conditions occurs:
^ The delivered torque PWM signal is less than 5 percent duty cycle or greater than 95 percent duty cycle.
^ The EBCM does not receive a delivered torque PWM signal for a period of 7 seconds.

Action Taken When the DTC Sets
^ The EBCM disables the TCS for the duration of the ignition cycle.
^ The TRACTION CONTROL indicator turns ON.
^ The ABS remains functional.

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
^ The condition for the DTC is no longer present (the DTC is not current) and you used the On-Board Diagnostics Clear DTC function.
^ The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
The following conditions can cause this concern:
^ An open in the delivered torque circuit.
^ An short to ground or voltage in the delivered torque circuit.
^ A wiring problem, terminal corrosion, or poor connection in the delivered torque circuit.
^ A communication frequency problem.
^ A communication duty cycle problem.
^ The EBCM is not receiving information from the PCM.
^ Loose or corroded EBCM ground or PCM ground.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step uses the scan tool to determine whether the delivered torque signal has a valid duty cycle.
4. This step measures whether the delivered torque signal has a valid duty cycle.
5. This step determines whether the PCM delivered torque signal has a valid frequency.