Circuit Description
Traction Control is simultaneously controlled by the EBCM and the Powertrain Control Module (PCM). The PCM sends a DELIVERED TORQUE message via a Pulse Width Modulated (PWM) signal to the EBCM confirming the delivered torque level for proper Traction Control system operation. The EBCM supplies the pull up voltage.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
DTC C1276 can be set anytime when ignition voltage is present. A malfunction exists if the PWM signal is out of range or no signal is received for a period of 7.0 seconds.
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 clear DTC function is used. |
| • | 100 ignition cycles have passed with no DTCs detected. |
Diagnostic Aids
| • | Possible causes for DTC C1276 to set are: |
| - | Delivered Torque line open. |
| - | Delivered Torque line shorted to ground. |
| - | Delivered Torque line shorted to voltage. |
| - | Communication frequency malfunction. |
| • | 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 Conditions and Poor Connections in Wiring Systems. |
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | |||||||||
2 | Inspect the following grounds, making sure each ground is clean and torqued to the proper specification:
Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 3 | ||||||||
3 |
Does the scan tool display within the specified range? | 5-95% | Go to Step 4 | Go to Step 5 | ||||||||
4 |
Important: Removing battery voltage or ground from the EBCM will result in the
following conditions:
Important: Disconnecting the EBCM connector and turning ON the ignition could cause
other modules to set loss of communication DTCs (Uxxxx). Once the EBCM is
reconnected, the EBCM may set one or both of the following DTCs:
Does the frequency measure within the specified range? | 121-134 Hz | Go to Step 8 | Go to Step 9 | ||||||||
5 | Test the delivered torque signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 6 | ||||||||
6 | Test the delivered torque signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 | ||||||||
7 | Test the delivered torque signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 | ||||||||
8 | Inspect the EBCM harness connector for poor connections/terminal tension. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 | ||||||||
9 | Inspect the PCM. Refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls. Did you find and correct the condition? | -- | Go to Step 11 | Go to Diagnostic Aids | ||||||||
10 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement Did you complete the repair? | -- | Go to Step 11 | -- | ||||||||
11 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
