Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0856: Engine Control Module (ECM) Traction Control Torque Request CircuitCircuit/System Description
The electronic brake control module (EBCM) and the engine control module (ECM) simultaneously control the traction control. The EBCM sends a serial data message to the ECM requesting torque reduction. When certain ECM DTCs are set, the ECM will not be able to perform the torque reduction for traction control. A serial data message is sent to the EBCM indicating that traction control is not allowed.
Conditions for Running the DTC
Engine running.
Conditions for Setting the DTC
The ECM diagnoses a condition preventing the engine control portion of the traction control function and sends a serial data message to the EBCM indicating that torque reduction is not allowed.
Action Taken When the DTC Sets
A DIC message and/or a warning indicator may be displayed.
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present. |
| • | The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
This DTC is for information only. As an aid to the technician, this DTC indicates that there are no problems in the ABS/traction control system (TCS).
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Antilock Brake System Connector End Views
Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Verify that there are no DTCs set in the ECM.
| ⇒ | If there are any DTCs set in the ECM, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
