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
| • | Ignition voltage is greater than 8 volts. |
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
| • | 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. |
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
- Ignition OFF, disconnect the VES actuator harness connector.
- 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. |
- 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. |
- 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.
- 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. |
- If all circuits test normal, test or replace the VES actuator.
Component Testing
- Ignition OFF, disconnect the VES actuator harness connector.
- 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. |
- 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.
