Diagnostic Instructions

DTC Descriptors

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

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

DTC C0450 04: Steering Assist Control Actuator Open Circuit

Circuit/System Description

The electronic brake control module (EBCM) commands current from 0-3 amps to the variable effort steering (VES) actuator, depending on vehicle speed. At low speeds, 0 amps of current is commanded to the actuator and the steering gear receives full flow of power steering fluid causing less effort to steer vehicle. As vehicle speed increases, the amount of amps increases to the actuator causing fluid to bypass steering gear. This limits hydraulic assist to steering gear causing firm steering. The EBCM monitors and compares the VES Commanded Current and VES Feedback Current parameters to detect malfunctions in the VES System.

Conditions for Running the DTC

Conditions for Setting the DTC

C0450 0B

The actuator current exceeds 4.5 amps.

C0450 02

The actuator current is detected as less than 50 percent of its expected current while the actuator is commanded OFF.

C0450 04

The current through the actuator is not within 0.5 amp of its commanded value.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Steering Assist Schematics

Connector End View Reference

Steering Assist Connector End Views

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With the engine ON, while turning the steering wheel, use a scan tool to command VES actuator ON. The steering wheel should take more effort to turn. Command the VES actuator OFF. The steering wheel should take less effort to turn.

Circuit/System Testing

1. Ignition OFF, disconnect the VES actuator harness connector.
2. Measure for 0 volts between the variable effort steering actuator supply voltage circuit and ground.

⇒	If over 0 volts, test the variable effort steering actuator supply voltage circuit for short to voltage. If the circuit tests normal, replace the EBCM.

3. Ignition ON, measure for B+ between the variable effort steering actuator supply voltage circuit and ground.

⇒	If under B+, test the variable effort steering actuator supply voltage circuit for short to ground or open/high resistance. If the circuit tests normal, replace the EBCM.

4. Connect a test lamp between the variable effort steering actuator supply voltage circuit and the variable effort steering actuator control circuit at the VES actuator harness connector.
5. Using a scan tool, command the VES actuator ON. Verify the test lamp illuminates.

⇒	If the test lamp does not illuminate, test the variable effort steering actuator control circuit for open/high resistance. If the circuit tests normal, replace the EBCM.

6. If all circuits test normal, test or replace the VES actuator.

Component Testing

1. Ignition OFF, disconnect the VES actuator harness connector.
2. Measure for 2.5-10 ohms of resistance between the VES actuator terminals.

⇒	If not 2.5-10 ohms of resistance, replace the VES actuator.

3. Measure for infinite ohms of resistance between each VES actuator terminal and the VES actuator housing.

⇒	If less than infinite ohms of resistance, replace the VES actuator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.