GM Service Manual Online
For 1990-2009 cars only

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 Descriptors

DTC C056E 42: ECU Hardware Performance Calibration Data Set Not Programmed

DTC C056E 4B: ECU Software Performance Calibration Not Learned

Circuit/System Description

After replacement of the power steering control module (PSCM), the PSCM must be configured with the proper tuning profile using the service programming system (SPS).

After replacement of the PSCM, power steering motor, or steering gear, the steering position/torque sensor calibration procedure must be performed.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

DTC C056E 42

This DTC will set if the PSCM has not undergone SPS programming.

DTC C056E 4B

This DTC will set if the PSCM, motor or torque sensor has not been calibrated using the steering position / torque sensor calibration procedure.

Actions Taken When DTC Sets

    • DTC is stored in memory.
    • The driver information center (DIC) displays the SERVICE POWER STEERING warning message.
    • Steering assist is set to a default level.

Conditions for Clearing the DTC

DTC C056E 42

A current or history DTC will clear after the PSCM has been configured with the proper tuning profile.

DTC C056E 4B

A current or history DTC will clear after the steering position/torque sensor calibration procedure has been performed.

Reference Information

Schematic Reference

Power Steering Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Steering System 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

  1. Verify DTC C056E 42 is not set.
  2. If DTC C056E 42 is set, perform the PSCM programming and setup procedures. If DTC C056E 42 resets, replace the PSCM.
  3. Verify DTC C056E 4B is not set.
  4. If DTC C056E 4B is set, perform the steering position/torque sensor calibration. If DTC C056E 4B resets, replace the PSCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PSCM replacement, setup, and programming