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 provides an overview of each diagnostic category.

DTC Descriptor

DTC C1528 00: Motor Speed Invalid Signal Malfunction

Circuit/System Description

The power steering control module (PSCM) monitors the pump motor circuits and sets a code for out of range signals.

Conditions for Running the DTC

Engine Running

Conditions for Setting the DTC

    •  Sensor signal is out of range.
    • Above condition must be fulfilled for at least 0.2 seconds.

Action Taken When the DTC Sets

The system function is not affected.

Conditions for Clearing the DTC

A history DTC will clear after 60 consecutive malfunction-free ignition cycles.

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

Circuit/System Verification

  1. Verify that DTC C1528 is set.
  2. If the DTC is set, reprogram the PSCM. If the DTC resets, replace the PSCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Important: For any module replacement a set procedure needs to be followed. A "Reset" needs to be performed from the PROGRAMMING menu of the current system with the scan tool BEFORE replacing the module.

    • Power Steering Pump Replacement
    • Power Steering Pump Wiring Harness Replacement