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 C1508 00: Internal Motor Circuit Malfunction

Circuit/System Description

The power steering control module (PSCM) continuously monitors the voltage and current levels being commanded to the power steering pump. The PSCM compares the commanded and feedback current levels to detect malfunctions in the power steering pump.

Conditions for Running the DTC

    • Engine running.
    • Power steering system voltage is 9-16 volts.
    • Steering input is present.

Conditions for Setting the DTC

A short to ground, short to voltage, or an open/high resistance in the power steering pump, or the circuits to the pump.

Action Taken When the DTC Sets

    • The driver information center (DIC) displays the POWER STEERING warning message.
    • No steering assist is provided.

Conditions for Clearing the DTC

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Verify DTC C1508 is not set.

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.

Power Steering Pump Replacement