GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 CTS 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC C0450

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 Descriptors

DTC C0450 02: Steering Assist Control Actuator Circuit Shorted to Ground

DTC C0450 0B: Steering Assist Control Actuator Circuit Current Above Threshold

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Variable Effort Steering Actuator Supply Voltage

C0450 02

C0450 0B

C0450 02

C0450 0B

Variable Effort Steering Actuator Control

C0450 02

C0450 0B

C0450 02

C0450 0B

Circuit/System Description

The electronic brake control module (EBCM) controls the current through the Variable Effort Steering (VES) actuator located on the steering gear. The current used to control the VES actuator is between 0 and 1 Amp. At low speeds and in parking lot maneuvers the current is applied to the actuator causing the orifice to open increasing fluid flow and reducing the steering effort. At high speeds the orifice is commanded closed by reducing current through the actuator and restricting fluid flow increasing steering effort. The EBCM monitors and compares the Commanded and Feedback Current parameters to detect malfunctions in the VES system.

Conditions for Running the DTC
    • The ignition is ON.
    • Ignition voltage is greater than 8 volts.

Conditions for Setting the DTC

C0450 0B

The actuator current exceeds 150mA.

C0450 02

If the solenoid feedback voltage is greater than 80 percent while the actuator is commanded ON.

Action Taken When the DTC Sets
    • The driver information center (DIC) will display SERVICE POWER STEERING message.
    • Vehicle speed will be limited to 80 mph.

Conditions for Clearing the DTC
    • The condition for setting the DTC is no longer present and the DTC is cleared with a scan tool.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

The vehicle may need to be driven to view full VES Actuator Commanded and Actuator Feedback Data parameters.

Reference Information

Schematic Reference

Power Steering Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Variable Effort Steering System Description and Operation

Electrical Information Reference

    •  Testing for Intermittent Conditions and Poor Connections
    •  Circuit Testing

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Important: It is recommended that Component Testing is performed before Circuit/System Testing when diagnosing the VES actuator because the module will default and does not supply voltage to the sensor when the DTC is set.

  1. Ignition OFF, disconnect the harness connector at the VES actuator.

    2. Important: In order to ensure correct test results, the J-35616 test lamp must be used to perform the following steps. Failure to use the J-35616 test lamp may result in inaccurate test results and potential misdiagnosis.

  2. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 1 and ground.
    3. ⇒If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the test lamp between the control circuit terminal 1 and the control circuit terminal 2.
  4. Ignition ON, verify the test lamp briefly illuminates for approximately 1 second, then turns OFF.
    5. ⇒If the test lamp is always ON, test the control circuit terminal 2 for a short to ground. If the circuit tests normal, replace the EBCM.
    ⇒If the test lamp is always OFF, test the control circuit terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the EBCM.
  5. If all circuits test normal, test or replace the VES actuator.

Component Testing
  1. Ignition OFF, disconnect the VES actuator harness connector terminal 1 and 2.
  2. Measure for 2.5-10 ohms of resistance between the VES actuator terminals.
    3. ⇒ If not 2.5-10 ohms of resistance, replace the VES actuator.
  3. Measure for infinite ohms of resistance between each VES actuator terminals and the VES actuator housing.
    4. ⇒ If less than the specified range, replace the VES actuator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for EBCM replacement, setup, and programming.
    •  Steering Gear Replacement