Scheme 1
Scheme 2
| Callout | Component Name |
|---|---|
| 1 | Magnasteer® Actuator |
Steering Controls Connector End Views
Magnasteer Actuator Connector Part Information 12052641 2-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function A WH 1294 Variable Effort Steering Actuator Supply Voltage B BN 1295 Variable Effort Steering Actuator Control
Diagnostic Starting Point - Variable Effort Steering
Begin the system diagnosis with the Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check will provide the following information
- The identification of the control modules which command the system
- The ability of the control modules to communicate through the serial data circuit
- The identification of any stored diagnostic trouble codes (DTCs) and their status
The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.
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 ABS wheel speed sensor inputs to determine vehicle speed. The EBCM commands current from negative 2 amps to positive 3 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.
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
- Ignition ON, and engine ON
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 VES output 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 malfunction-free ignition cycles.
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.
- 2: This step tests if the VES malfunction is current or intermittent.
- 3: This step tests if the VES actuator resistance is in the specified range.
- 13: Perform the programing procedure after EBCM replacement.
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Steering Controls Schematics Connector End View Reference: Steering Controls Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | Turn ON the ignition, with the engine OFF. Select the diagnostic trouble codes (DTC) function with the scan tool. Does the scan tool indicate that DTC C0450 is a history DTC ? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |
| 3 | Turn OFF the ignition. Disconnect the variable effort steering (VES) actuator harness connector. Measure the resistance of the VES actuator. Does the resistance measure within the specified range? | 1.6-3.1 ohms | Go to Step 6 | Go to Step 10 |
| 4 | 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 5 | Go to Step 6 | |
| 5 | Visually inspect the actuator harness for any cut, chaffed, or damaged wires. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 | |
| 6 | 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 . Did you find and correct the condition? | Go to Step 14 | Go to Step 7 | |
| 7 | Test the high effort control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 8 | |
| 8 | Test the low effort control circuit 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 14 | Go to Step 9 | |
| 9 | Test the low effort control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 11 | |
| 10 | 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 14 | Go to Step 12 | |
| 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 14 | Go to Step 13 | |
| 12 | Replace the VES actuator. Refer to Power Steering Gear Replacement . Did you complete the repair? | Go to Step 14 | ||
| 13 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the repair? | Go to Step 14 | ||
| 14 | Clear the DTCs with the scan tool. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does DTC C0450 reset? | Go to Step 2 | System OK | |
DTC C0450
The Variable Effort Steering (VES) system or MAGNASTEER® Varies the amount of effort required to steer the vehicle as vehicle speed changes. At low speeds, the system provides minimal steering effort for easy turning and parking Maneuvers. Steering effort is increased at higher speeds to provide firmer steering (road feel) and directional stability. The Electronic Brake Control Module (EBCM) controls a bi-directional magnetic rotary actuator located in the steering rack and pinion. The EBCM varies the steering assist by adjusting the current flow through the actuator to achieve a given level of effort to steer the vehicle. The VES system accomplishes this by adding or subtracting torque on the input shaft to the rack and pinion. The main component of the system is an electromagnetic actuator, which consists of a multiple-pole ring-style permanent magnet, a pole piece, and an electromagnetic coil assembly. The VES system uses the ABS wheel speed sensor inputs to determine vehicle speed. When the EBCM senses wheel speed, it commands a current to the VES actuator that is most appropriate for each speed. The EBCM commands current from negative two amps to positive three amps to the actuator, which is polarized. 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. Ignition voltage and ground are provided through the EBCM. The EBCM has the ability to detect malfunctions in the actuator or the circuits to the actuator. Any malfunctions detected will cause the system to ramp to zero amps and steering will be assisted by hydraulics only and setting a DTC.
See also:
• Diagnostic System Check - Vehicle
• Testing for Intermittent Conditions and Poor Connections
• Testing for Short to Ground
• Wiring Repairs
• Circuit Testing
• Connector Repairs
• Power Steering Gear Replacement
• Electronic Brake Control Module Replacement
• Steering Controls Schematics
• Steering Controls Connector End Views