Circuit Description
The variable effort steering (VES) system uses the electronic brake control module (EBCM) to control current to a bi-directional electromagnetic rotary actuator. The EBCM commands current from negative 3 amps to positive 3 amps to the actuator. At low speeds, less than approximately 24 km/h (15 mph), negative three amps of current is commanded, providing maximum assist to steering. As speed increases, increased (more positive) current is commanded, reaching zero amps at approximately 96 km/h (60 mph). The EBCM commands positive current only during steering input at higher speeds, based on the above inputs and the vehicle calibration, which creates steering resistance.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0450 Steering Assist Control Solenoid/Motor/Actuator Circuit
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
| • | 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 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.
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This step tests if the Actuator Commanded and Actuator Feedback Current parameters are within specification in their active state.
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Perform the VES test located under Special Functions. This test may indicate if the VES actuator is mechanically bound.
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This step tests if the resistance of the VES actuator is within specification.
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This step tests the control circuit of the VES actuator for a short to ground.
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Perform the setup procedure after EBCM replacement.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Steering Assist Schematics Connector End View Reference: Steering Assist Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
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 amp | Go to Step 3 | Go to Step 4 | |
Select F2: VES Test with the scan tool. Does the scan tool indicate Test Passed? | -- | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 4 | |
Does the resistance measure within specified range? | 1.6-3.1 ohms | 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 |
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 find and correct the condition? | -- | 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 find and correct the condition? | -- | 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 . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
|
Important: Perform the setup procedure for the EBCM. Replace and reprogram the EBCM. Refer to Control Module References . 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 |
Does DTC C0450 reset? | -- | Go to Step 2 | System OK |
