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 overview of each diagnostic category.

DTC Descriptor

DTC C0475 00: Electric Steering Motor Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open or High Resistance

Short to Voltage

Signal Performance

Motor

C0475 00*

C0475 00*

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*After verifying a circuit fault exists in the power steering wiring harness extension harness for two mode hybrid. The wiring harness is to be replaced and not repaired

Circuit/System Description

The power steering control module (PSCM) continuously monitors the voltage and current levels being commanded to the electric power steering (EPS) motor. The 42-volt circuit from the accessory power module (APM) supplies power to the PSCM pulse width modulated control circuit to drive the 3 phase motor. The PSCM compares the desired and actual current levels to detect malfunctions in the EPS motor, or the circuits to the motor.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

The PSCM detects an open, or a short to ground on any of the motor phase circuits.

Actions Taken When DTC Sets

    • 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.

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

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure will perform the following tasks:

   • Identify how to disable high voltage.
   • Identify how to test for the presence of high voltage.
   • Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.
Failure to follow the procedures exactly as written may result in serious injury or death.

Important: After verifying a circuit fault exists in the Power Steering Assist Motor Wiring Harness for Two Mode Hybrid, the Power Steering Assist Motor is to be replaced and not repaired

  1. Perform the High Voltage Disabling procedure.
  2. Ignition OFF, connect the 12-volt battery.
  3. Ignition OFF, disconnect the harness connector at the PSCM.
  4. Test for less than 1 Ω between the following circuits listed below.
  5. • Control circuit terminal 2 and control circuit terminal 1
    • Control circuit terminal 1 and control circuit terminal 3
    • Control circuit terminal 2 and control circuit terminal 3
    If greater than the specified range, replace the power steering assist motor.
  6. Test for greater than infinite resistance between the following circuits listed below and the power steering motor housing.
  7. • Control circuit terminal 2
    • Control circuit terminal 1
    • Control circuit terminal 3
    If less than the specified range, replace the power steering assist motor.
  8. If all circuits test normal, test or replace the PSCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Power Steering Assist Motor Replacement
    •  Control Module References for PSCM replacement, setup, and programming