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 C1527 0B: Motor Circuit High Current Above Threshold

DTC C1527 01: Motor Circuit High Current Short to Battery

DTC C1529 00: Motor Circuit Low Current Malfunction

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Power Steering Pump Motor

C1529 00

C1529 00

C1527 01,C1527 0B

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Circuit/System Description

The power steering control module (PSCM) monitors the motor amperage to ensure that the amperage stays within proper range. Damage to components and incorrect data may occur when the amperage is out of range.

Conditions for Running the DTC

    • Engine Running or Engine Starting (see below)
    • Power steering pump motor amperage is 55-65 Amps with the steering wheel turned and held full right or left.

Conditions for Setting the DTC

DTC C1527 0B, 01

The actual motor current is greater than 75 Amps for at least 1.0 second during ignition ON and engine starting.

DTC C1529 00

The actual motor current is less than 11 amps during engine starting.

Action Taken When the DTC Sets

DTC C1527 0B, 01

Steering boost is switched OFF.

DTC C1529 00

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Actual Pump Motor Current

  1. Ignition OFF, Wait 3 seconds, Ignition ON, All accessories OFF with a scan tool verify Actual Motor Current to be 0 Amps
  2. Ignition ON, Engine ON, All accessories OFF, the Actual Motor Current should be 4 to 5 Amps.
  3. Turn steering wheel right until stop, turn slightly further and hold firmly in this position. The Actual Motor Current should be between 55-65 Amps.
  4. Turn steering wheel left until stop, turn slightly further and hold firmly in this position. The Actual Motor Current should be between 55-65 Amps.
  5. If the amperage is not within the specified range, replace the power steering control module.

Desired Pump Speed

  1. Ignition OFF, Wait 3 seconds, Ignition ON, All accessories OFF with a scan tool verify the Desired Pump Speed is 0.
  2. Engine Running, with a scan tool verify the Desired Pump Speed is 2660.
  3. If the RPM is not specified value, replace the power steering control module.
    If the RPM is the specified value, refer to the Actual Pump Speed.

Actual Pump Speed

  1. Ignition OFF, Wait 3 seconds, Ignition ON, All accessories OFF, with a scan tool verify the Actual Pump Speed is 0.
  2. Engine Running, with a scan tool verify the Actual Pump Speed is 2655-2665 RPM.
  3. If the RPM is not within the specified range, replace the power steering control module.

Repair Instructions

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

    • Perform the Diagnostic Repair Verification after completing the repair.
    •  Power Steering Pump Replacement
    •  Power Steering Pump Wiring Harness Replacement