C1277

DTC C1277 Requested Torque Signal Circuit Malfunction (Part 1 Of 2):

DTC C1277 Requested Torque Signal Circuit Malfunction (Part 2 Of 2):

Torque Signal Circuit Schematic:

CIRCUIT DESCRIPTION
"Traction control" is simultaneously controlled by the EBTCM and the PCM. The PCM receives a "REQUESTED TORQUE" request via a Pulse Width Modulated (PWM) signal from the EBTCM requesting the desired torque level for proper "Traction Control" system operation. The PCM supplies the pull up voltage.

CONDITION FOR SETTING THE DTC
There is an open or short in the "REQUESTED TORQUE" line between the EBTCM and PCM or there is a "TCS" communication malfunction detected by the PCM and indicated to the EBTCM, by broadcasting a PWM message.

ACTION TAKEN WHEN THE DTC SETS
A malfunction DTC is stored, TCS is disabled and the "TRACTION OFF" indicator lamp is turned "ON." ABS remains functional.

CONDITIONS FOR CLEARING DTC
- Condition for DTC is no longer present and scan tool clear DTC function is used.
- 50 ignition cycles have passed with no DTC(s) detected.

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.
Possible causes:
- Open in CKT 463.
- CKT 463 shorted to ground or voltage.
- Communication frequency problem.
- PCM not receiving information from EBTCM.

NOTE: 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.

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