Antilock Brake System

DTC C0450

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



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




Diagnostic Fault Information






Circuit/System Description

The electronic brake control module (EBCM) controls the variable effort steering actuator on the steering gear. At low speeds and parking lot maneuvers the orifice is commanded open increasing fluid flow and reducing the steering effort. At high speeds the office is commanded closed 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 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

Antilock Brake System Schematics (Except JL7) (Antilock Brake System Schematics (Except RPO JL7))Antilock Brake System Schematics (JL7) (Antilock Brake System Schematics (With RPO JL7))
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for Scan Tool Information


Circuit/System Verification

At low speeds and parking lot maneuvers the orifice is commanded open increasing fluid flow and reducing the steering effort. At high speeds the orifice is commanded closed restricting fluid flow increasing steering effort.


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the VES actuator.
2. Connect a test lamp between the low effort control circuit terminal A and ground.
3. Cycle the ignition ON and verify the test lamp turns ON then OFF.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the EBCM.


• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.

4. Connect a test lamp between the control circuit terminals A and B.
5. Cycle the ignition ON and verify the test lamp turns ON then OFF.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the EBCM.


• If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.

6. Ignition OFF, disconnect the harness connector at the EBCM.
7. Test for infinite resistance between the control circuit terminal 29 and ground.

• If not the specified value, test the control circuit for a short to ground.

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



Component Testing

1. Ignition OFF, disconnect the VES actuator harness connector terminal A and B.
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 terminals and the VES actuator housing.

• If less than the specified range, replace the VES actuator.




Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Control Module References (Programming and Relearning) for EBCM replacement, setup, and programming