P0856

DTC C0561 or P0856

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 C0561 71
- System Disabled Information Stored

DTC P0856
- Traction Control Torque Request Circuit




Circuit/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

The ignition is ON.


Conditions for Setting the DTC

The engine control module (ECM) detects a fault preventing the engine traction control and sends a serial data message to the EBCM indicating that torque reduction is not allowed.


Action Taken When the DTC Sets

One or more of the following actions may occur:

* The EBCM disables the engine traction system (ETS) for the entire ignition cycle.
* The traction Off Indicator illuminates.
* The antilock brake system (ABS) remains functional.



Conditions for Clearing the DTC

* The condition for the DTC is no longer present.
* The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.



Diagnostic Aids

This information is an aid to the technician, this DTC indicates that there are no problems in the ABS/TCS. The ECM should be checked for a possible fault .


Reference Information
Schematic Reference

Antilock Brake System Schematics ([1][2]Antilock Brakes / Traction Control Systems)
Connector End View Reference

Component Connector End Views
Description and Operation

ABS Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information


Circuit/System Verification

Verify that no DTCs are set in the ECM.

If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle