For 1990-2009 cars

### Circuit 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 in the retracted position. At high speeds, no current is commanded to the actuator and the valve moves closer to the power steering fluid orifice. The EBCM monitors and compares the VES Commanded Current and VES Feedback Current parameters to detect malfunctions in the VES system.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0450 Steering Assist Control Solenoid/Motor/ Actuator Circuit

### Conditions for Running the DTC

• | The ignition voltage between is 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

• | 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 clears when the malfunction is no longer present.

• | A history DTC will clear after 100 ignition cycles.

### Diagnostic Aids

The vehicle may need to be driven to view full VES Actuator Commanded and Actuator Feedback Data parameters.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step tests if the Actuator Commanded and Actuator Feedback Current parameters are within specification in their active state.

2. Perform the VES test located under Special Functions. This test may indicate if the VES actuator is mechanically bound.

3. This step tests if the resistance of the VES actuator is within specification.

4. This step tests the control circuit of the VES actuator for a short to ground.

5. Perform the setup procedure after EBCM replacement.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Steering Controls Schematics Connector End Views Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Start the engine.
2. Observe the VES Actuator Commanded Current and VES Actuator Feedback Current Data parameters in the VES data list for the EBCM with a scan tool.

Are the VES Actuator Commanded Current and VES Actuator Feedback Current parameters within 0.03 amps of each other and within the specified range?

0.9-1 A

Go to Step 3

Go to Step 4

3 | Using the scan tool, select F2: VES Test. Does the scan tool indicate Test Passed? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 4
4 |

1. Turn OFF the ignition.
2. Disconnect the variable effort steering (VES) actuator harness connector.
3. Measure the resistance of the VES actuator.

Does the resistance measure within the specified range?

5.7-7.2 Ω

Go to Step 5

Go to Step 12

5 | Test the VES actuator and actuator harness for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs. Was a short to ground located? | -- | Go to Step 6 | Go to Step 7
6 | Inspect the actuator harness for any cut, chaffed, or damaged wires. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14
7 | Test the control circuit of the VES actuator for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 8
8 | Test the control circuit of the VES actuator for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 9
9 | Test the return circuit of the VES actuator for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs. Did you complete the replacement? | -- | Go to Step 15 | Go to Step 10
10 | Test the return circuit of the VES actuator for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs. Did you complete the replacement? | -- | Go to Step 15 | Go to Step 11
11 | Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13
12 | Inspect for poor connections at the harness connector of the VES actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. | -- | Go to Step 15 | Go to Step 14
13 | Note: Perform the setup procedure for the EBCM. Replace and reprogram the EBCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | -- | Go to Step 15 | --
14 | Replace the VES actuator. Refer to Steering Gear Replacement. Did you complete the replacement? | -- | Go to Step 15 | --
15 |

1. Clear the DTCs with the scan tool.
2. Operate the vehicle with in the Conditions for Running the DTC.

Does DTC C0450 reset?

--

Go to Step 2

System OK