Scheme 1
Scheme 2
| Callout | Component Name |
|---|---|
| 1 | Power Steering Reservoir |
| 2 | Steering Column Shaft Cover |
| 3 | MagnaSteer® Actuator |
| 4 | Power Steering Pump |
Steering Controls Connector End Views
Magnasteer Actuator (LY7) Connector Part Information OEM: 12052641 Service: 12102747 2-Way F Metri-Pack 150 Series, Sealed (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 CODE INDEX
| DTC | Description |
|---|---|
| DTC C0450 | Steering Assist Control Solenoid/Motor/Actuator Circuit |
DIAGNOSTIC CODE INDEX
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 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.
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
- 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.
Diagnostic Aids
The vehicle may need to be driven to view full VES Commanded and Feedback Data parameters
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step tests if the Commanded and Feedback Current parameters are within specification in their active state.
- 3: Perform the VES test located under Special Functions. This test may indicate if the VES actuator is mechanically bound.
- 4: This step tests if the resistance of the VES actuator is within specification.
- 7: This step tests the control circuit of the VES actuator for a short to ground.
- 13: Perform the setup procedure after EBCM replacement.
| Step | Action | Values | 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 in Vehicle DTC Information | |
| 2 | Start the engine. With a scan tool, observe the VES Commanded Current and VES Feedback Current Data parameters in the VES data list for the EBCM. Does the scan tool display the VES Commanded and Feedback Current Data parameters are within 0.03 amps of each other and within specified range? | 0.90-1.00 A | Go to Step 3 | Go to Step 4 |
| 3 | Using the scan tool, select F1 VES Test. Does the scan tool indicate Test Passed? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 4 | |
| 4 | 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 specified range? | 5-10 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 in Wiring Systems. Was a short to ground located? | Go to Step 6 | Go to Step 7 | |
| 6 | Visually 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 | |
| 7 | Test the control circuit of the VES actuator 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 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. 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 in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 14 | |
| 13 | IMPORTANT: Always perform the setup procedure for the EBCM. Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Perform the setup procedure for the EBCM. Did you complete the replacement? | Go to Step 15 | ||
| 14 | Replace the VES actuator. Refer to Power Steering Gear Replacement in Power Steering System. Did you complete the replacement? | Go to Step 15 | ||
| 15 | Clear the DTCs with the scan tool. Operate the vehicle within the Conditions for Running the DTC. Does DTC C0450 reset? | Go to Step 2 | System OK | |
| IMPORTANT |
|---|
| Always perform the setup procedure for the EBCM. |
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 for increased 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 set 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
• Electronic Brake Control Module Replacement
• Power Steering Gear Replacement
• DTC C0450
• Steering Controls Connector End Views