Diagnostic Instructions
DTC Descriptor
DTC C0450: Steering Assist Control Solenoid/Motor/Actuator Circuit
Circuit/System 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.
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
The EBCM detects an open, short to ground, or short to voltage in the VES actuator or the actuator circuits.
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
| • | The condition for setting the DTC is no longer present. |
| • | The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
The vehicle may need to be driven to view full VES Actuator Commanded and Actuator Feedback Data parameters.
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
Scan Tool Reference
Control Module References
Circuit/System Testing
- Ignition OFF, disconnect the VES actuator harness connector.
- Measure for 0 volts between the variable effort steering actuator supply voltage circuit terminal A and ground.
| ⇒ | If the voltage is greater than the specified range, test the variable effort steering actuator supply voltage circuit for short to voltage. If the circuit tests normal, replace the EBCM. |
- Ignition ON, measure for 12 volts between the variable effort steering actuator supply voltage circuit terminal A and ground.
| ⇒ | If the voltage is less than the specified range, test the variable effort steering actuator supply voltage circuit for short to ground or open/high resistance. If the circuit tests normal, replace the EBCM. |
- Connect a test lamp between the variable effort steering actuator supply voltage circuit terminal A and the variable effort steering actuator control circuit terminal B at the VES actuator harness connector.
- Using a scan tool, command the VES actuator ON. Verify the test lamp illuminates.
| ⇒ | If the test lamp does not illuminate, test the variable effort steering actuator control circuit for open/high resistance. If the circuit tests normal, replace the EBCM. |
- If all circuits test normal, test or replace the VES actuator.
Component Testing
- Ignition OFF, disconnect the VES actuator harness connector.
- Measure for 5-10 ohms of resistance between the VES actuator terminals A and B.
| ⇒ | If the resistance is outside the specified range, replace the VES actuator. |
- Measure for infinite ohms of resistance between each VES actuator terminal and the VES actuator housing.
| ⇒ | If less than the specified range, replace the VES actuator. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
