For 1990-2009 cars

### 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 00: Steering Assist Control Solenoid Actuator Circuit
DTC C0450 5A: Steering Assist Control Solenoid Actuator Circuit plausibility failure

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Variable Effort Steering High Control | C0450 5A | C0450 5A | C0450 5A | --
Variable Effort Steering Low Control | C0450 5A | C0450 5A | C0450 5A | --

### Circuit/System Description

The electronic brake control module (EBCM) controls the variable effort steering (VES) actuator on the steering gear. As speed increases the EBCM commands the amperage to the actuator to a max of 1A, this closes the orifice and restricts fluid flow for a firm steering effort. At low speeds and parking lot maneuvers the orifice is normally open allowing maximum fluid flow for an easy steering effort.

### Conditions for Running the DTC

• | Ignition ON.

• | Engine OFF test -- Initial ignition ON, no engine RPM or vehicle speed present.

• | Engine ON test -- If Engine OFF test passes, engine RPM and vehicle speed present.

### Conditions for Setting the DTC

A short to voltage, short to ground, or open/high resistance is detected on the high control or low control circuit.

### Action Taken When the DTC Sets

• | The ABS and red brake warning indicators illuminate.

• | The driver information center (DIC) displays SERVICE STEERING SYSTEM.

• | 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

Power Steering Schematics

#### Connector End View Reference

Component 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

Control Module References for scan tool information

### Circuit/System Verification

Engine running, using a scan tool perform the VES Actuator test. Command the actuator while turning the steering wheel, the effort should increase when commanded between 10-100%.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the VES actuator.
2. Ignition ON, Command the VES actuator to 100% with a scan tool.
3. Test for B+ between the high control circuit terminal 2 and ground.

⇒ | If not the specified value, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.

4. Connect a DMM, set on the diode setting, between the low control circuit terminal 1 and ground.
5. Command the VES actuator to 0% with a scan tool. The DMM reading should be greater than 2.5 volts or display O.L.

⇒ | If less than the specified value, test the low control circuit for a short to voltage or a short to ground. If the circuit tests normal, replace the EBCM.

6. Command the VES actuator to 100% with a scan tool. The DMM reading should be less than 1 volt.

⇒ | If greater than the specified range, test the low control circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.

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

### Component Testing

1. Ignition OFF, disconnect the harness connector at the VES actuator.
2. Test for 5-10 ohms between the control terminals 1 and 2.

⇒ | 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.

• | Steering Gear Replacement

• | Control Module References for EBCM replacement, setup, and programming