Diagnostic Instructions
DTC Descriptor
DTC C0450: Steering Assist Control Solenoid/Motor/Actuator Circuit
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
Description and Operation
Variable Effort Steering System Description and Operation
Electrical Information Reference
Scan Tool Reference
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
- Ignition OFF, disconnect the harness connector at the VES actuator.
- 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. |
- 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. |
- If all circuits test normal, test or replace the VES actuator.
Component Testing
Variable Effort Steering Actuator Test
- Ignition OFF, disconnect the harness connector at the VES actuator.
- 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. |
- 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.
