Service Information

Cruze

DTC 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 P0856 00: Traction Control Torque Request Circuit Malfunction

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.

•	The EBCM will turn OFF the indicator in the next ignition cycle.

Reference Information

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 Testing

Verify that no DTCs except P0856 00 are present in the K20 ECM.

⇒	If any DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Replace the K20 ECM and verify the DTC does not reset.

⇒	If the DTC resets, replace the K17 EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for EBCM or ECM replacement, programming and setup