For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2007 🢒 Equinox 🢒 Steering 🢒 Power Steering 🢒 DTC C056D, C120C, C121C, C121E, C121F, C123A-C123F, C1255, C1256, C126E, C126F, C127E, C12A7, C12C2, C12C5, C12C6, C12C8, C12CC, C12CF, C12D0-C12DF, or C12E0

DTC C056D, C120C, C121C, C121E, C121F, C123A-C123F, C1255, C1256, C126E, C126F, C127E, C12A7, C12C2, C12C5, C12C6, C12C8, C12CC, C12CF, C12D0-C12DF, or C12E0 for Chevrolet Equinox 2007

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 provide an overview of each diagnostic category.

DTC Descriptor

DTC C056D 39: ECU Hardware Performance Internal Electronic Failure

Circuit/System Description

The power steering control module (PSCM) continuously monitors the internal circuitry within the module.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

This DTC will set if the PSCM detects an internal malfunction within the module.

Actions Taken When DTC Sets

•	DTC C056D is stored in memory.

•	The driver information center (DIC) displays the SERVICE POWER STEERING warning message.

•	No steering assist.

Conditions for Clearing the DTC

•	A current DTC will clear on the next malfunction free ignition cycle.

•	A history DTC will clear after 100 consecutive malfunction-free ignition cycles, without the repeat of the internal malfunction.

Reference Information

Electrical Information Reference

•	Testing for Intermittent Conditions and Poor Connections

•	Circuit Testing

Scan Tool Reference

•	Scan Tool Data List

•	Scan Tool Data Definitions

Circuit/System Verification

Verify that DTC C056E is not set.

⇒	If DTC C056E is set, program the PSCM. If DTC C056D resets, replace the PSCM.

Replace the PSCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.