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 VES system also uses the Antilock Brake System (ABS) wheel speed sensor inputs to determine vehicle speed. The EBCM commands current from negative two amps to positive three amps to the VES actuator. At low speeds, a negative current is commanded, which assists steering. At medium speeds, no current is commanded and steering is assisted by hydraulics only. At high speeds, a positive current is commanded, 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
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 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 no malfunction present. |
| • | Using the scan tool |
Diagnostic Aids
A short to voltage on the High or Low effort circuits to the VES actuator can also cause DTCs C0236, C0244, U1000, U1016, or U1064 to set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Tests if the commanded and feedback current parameters are at the specified value in there active state.
-
Tests if the VES actuator resistance is in the specified range.
-
Perform the setup procedure after EBCM replacement.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Steering Assist Schematics | ||||||||
1 | Did you perform the Variable Effort Steering Diagnostic System Check? | -- | Go to Step 2 | |||||
Does the scan tool indicate that the DTC C0450 is a history DTC? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |||||
Does the resistance measure within the specified range? | 1.6-3.1 ohms | Go to Step 4 | Go to Step 8 | |||||
4 | Test the High Effort Control circuit of the VES actuator for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring System. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 5 | ||||
5 | Test the High Effort Control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 6 | ||||
6 | Test the Low Effort Control circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||
7 | Test the Low Effort Control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||
8 | Inspect for poor connections at the harness connector of the VES actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||
9 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 | ||||
10 | Replace the VES actuator. Refer to Steering Gear Replacement in Power Steering System. Did you complete the repair? | -- | Go to Step 12 | -- | ||||
11 |
Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will
result in the following conditions:
Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Did you complete the repair? | -- | Go to Step 12 | -- | ||||
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||
