C0450

DTC C0450

DTC Descriptor

DTC C0450
- Steering Assist Control Solenoid/Motor/Actuator Circuit

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

Circuit/System Description

The electronic brake control module (EBCM) commands current from 0-1 amp to the variable effort steering (VES) actuator, depending on vehicle speed. At low speeds, 1-amp of current is commanded to the actuator and the actuator valve is fully closed. A speed increases, less current is commanded to the actuator and the valve opens, allowing pressure to bleed off through a power steering fluid orifice. The EBCM monitors and compares the Commanded and Feedback Current parameters to detect malfunctions in the VES system.

Conditions for Running the DTC

* Ignition voltage between 10.5-17 volts
* Off state test-Initial ignition ON, no engine RPM or vehicle speed present.
* On state test-If off state test passes, engine RPM and vehicle speed present.

Conditions for Setting the DTC

An open, short to ground or short to voltage in the VES actuator or the circuits to the actuator.

Action Taken When the DTC Sets

* A DTC C0450 is stored in memory.
* The driver information center (DIC) displays the SERVICE STEERING SYSTEM warning message.
* The VES system is disabled for the remainder of the ignition cycle.

Conditions for Clearing the DTC

* A current DTC will clear when the malfunction is no longer present.
* A history DTC will clear after 100 consecutive ignition cycles with the malfunction no longer present.

Reference Information

Schematic Reference

Steering Assist Schematics

Connector End View Reference

* Steering Assist Connector End Views
* Antilock Brake System Connector End Views

Description and Operation

Variable Effort Steering System Description and Operation

Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs

Scan Tool Reference

* Scan Tool Data List
* Scan Tool Data Definitions
* Scan Tool Output Controls

Circuit/System Verification

Perform the VES Actuator test with a scan tool and turn the steering wheel, the effort should increase and decrease and then back to normal.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the VES actuator.
2. Ignition ON, verify that a test lamp illuminates between control circuit terminal A and ground.

^ If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.

3. Verify that a test lamp illuminates between control circuit terminal B and ground.

^ If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.

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

Component Testing

Variable Effort Steering Actuator Test

1. Ignition OFF, disconnect the harness connector at the VES actuator.
2. Test for 5-10 ohms of resistance between control terminal A and control terminal B.

^ If not within the specified range, replace the VES actuator.

3. Test for infinite resistance between each terminal and the VES actuator housing/case.

^ If not the specified value, replace the VES actuator.

Repair Instructions

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

* Power Steering Gear Solenoid/Actuator Replacement
* Refer to Programming and Relearning.