P0856

DTC C0242 or P0856

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.

DTC Descriptor
DTC C0242 00
- Engine Control Module Indicated Traction Control Malfunction

DTC P0856 00
- Traction Control Torque Request Circuit Malfunction

Circuit/System Description

When traction control is active, the electronic brake control module (EBCM) sends a serial data message to the engine control module (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 detects a fault that prevents it from performing a 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

* The EBCM disables the traction control and stability control for the duration of the ignition cycle.
* The traction control/stability control-active indicator turns ON.

Conditions for Clearing the DTC

A current DTC clears when the diagnostic runs and passes.

Reference Information
Schematic Reference

Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

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

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

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Testing

1. Verify that no DTCs except P0856 are present in the ECM.

• If any DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) to diagnose that DTC prior to this diagnostic.

2. Replace the K20 Engine Control Module and verify the DTC does not reset.

• If the DTC resets replace the K17 Electronic Brake Control Module (EBCM).

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning)for EBCM or ECM replacement, programming, and setup