DTC P0856. Chevrolet Caprice WM 2008

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2008 🢒 Caprice WM 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 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: Engine Control Module (ECM) Traction Control Torque Request Circuit

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

•	The Traction Off indicator turns ON.

•	The message center displays the Service Traction System message.

•	The antilock brake system (ABS) remains functional.

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

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 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 .