Circuit Description
Traction Control is simultaneously controlled by the EBTCM and the Powertrain Control Module (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.
Conditions for Setting the DTC
DTC C1277 can be set when 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 Class 2 message.
Action Taken When the DTC Sets
| • | A malfunction DTC is stored. |
| • | 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 (CKT463) open. |
| - | Requested Torque line (CKT463) shorted to ground. |
| - | Requested Torque line (CKT463) 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 Intermittents and Poor Connections Diagnosis in Wiring Systems. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | ||
2 |
Is the resistance within the range specified in the Value(s) column? | 0-2 ohms | ||
3 | Repair CKT 463 for an open or high resistance. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
4 |
Is CKT 463 shorted to ground? | -- | ||
5 | Repair CKT 463 for a short to ground. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
6 |
Is any voltage present on CKT 463 with the ignition ON? | -- | ||
7 | Repair CKT 463 for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
8 |
Is the voltage within the range specified in the Value(s) column? | 4.5-5.5 V | ||
9 | Replace the EBTCM. Refer to Electronic Brake Control Module/Electronic Brake and Track Control Module Replacement . Is the replacement complete? | -- | -- | |
10 | Suspect the PCM. Refer to Powertrain On Board Diagnostic (OBD) System Check or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls. Is the diagnosis complete? | -- | -- |
