Steering Controls Schematic Icons
Steering Controls Schematic Icons Icon Icon Definition IMPORTANT: Twisted-pair wires provide an effective shield that helps protect sensitive electronic components from electrical interference. If the wires were covered with shielding, install new shielding. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 10 turns per 31 cm (12 in) as measured anywhere along the length of the wires The outside diameter of the twisted wires must not exceed 6.0 mm (0.25 in)
Scheme 1
Scheme 2
Scheme 3
| Callout | Component Name |
|---|---|
| 1 | Power Steering Rack (LHD) |
| 2 | Variable Effort Steering Actuator (LHD) |
| 3 | Variable Effort Steering Actuator Wiring Harness |
Scheme 4
| Callout | Component Name |
|---|---|
| 1 | Power Steering Rack (RHD) |
| 2 | Variable Effort Steering Actuator (RHD) |
Steering Controls Connector End Views
Variable Effort Steering Actuator (FE3) Connector Part Information 12052641 2-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function A GY 1787 Variable Effort Steering Actuator High Effort Control B WH 345 Variable Effort Steering Actuator Low Effort Control
Diagnostic Starting Point - Variable Effort Steering
Begin the system diagnosis with the Diagnostic System Check - Variable Effort Steering . 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.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: The lack of communication may be caused by a partial or a total malfunction of the circuit containing the class 2 serial data. The specified procedure will determine the particular condition.
- 3: Tests for other electronic brake control module (EBCM) controlled subsystem malfunctions that may use the same inputs as the variable effort steering (VES) system.
- 4: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will collect all the available information before tests are performed.
- 5: Tests if the malfunction lies specifically in the VES system.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Steering Controls Schematics | |||
| 1 | Install a scan tool. Does the scan tool turn ON? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications |
| 2 | Turn ON the ignition, with the engine OFF. Attempt to establish communication with the EBCM. Does the scan tool communicate with the EBCM? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications |
| 3 | Select the ABS Diagnostic Trouble Codes function on the scan tool. Does the scan tool display any DRP/ABS/TCS or VSES DTCs? | Go to Diagnostic System Check - ABS in Antilock Brake System | Go to Step 4 |
| 4 | Does the scan tool display any DTCs which begin with a "U"? | Go to Diagnostic Trouble Code (DTC) List in Data Link Communications | Go to Step 5 |
| 5 | Does the scan tool display "DTC C0450?" | Go to Diagnostic Trouble Code (DTC) List | System OK |
Diagnostic System Check - Variable Effort Steering
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selections | Description |
|---|---|---|
| VES actuator | VES test | The Electronic Brake Control Module (EBCM) can be commanded using the scan tool to perform a self-test varying steering effort from more firm, to less firm, to more firm, then back to normal. |
Scan Tool Output Controls
Scan Tool Data List
| Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
| Ignition ON/ engine ON/ no vehicle speed present | |||
| ABS Reference Speed | VES Data | Mph | 0 |
| LF Wheel Speed | VES Data | Mph | 0 |
| LR Wheel Speed | VES Data | Mph | 0 |
| RF Wheel Speed | VES Data | Mph | 0 |
| RR Wheel Speed | VES Data | Mph | 0 |
| Ignition Voltage | VES Data | Volts | 13.25 |
| Switched System Battery Voltage | VES Data | Volts | 13.25 |
| VES Failed | VES Data | Yes/No | No |
| VES Indicator Message | VES Data | On/Off | Off |
| VES Commanded Current | VES Data | Amps | 1.00 |
| VES Feedback Current | VES Data | Amps | 1.00 |
Scan Tool Data List
Diagnostic Trouble Code (DTC) List
| DTC | Diagnostic Procedure | Module(s) |
|---|---|---|
| C0450 | DTC C0450 | EBCM |
Diagnostic Trouble Code (DTC) List
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, one amp of current is commanded to the actuator and the actuator valve is in the retracted position. At high speeds, no current is commanded to the actuator and the valve moves closer to the 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 10.5-17.0 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.
- Using a scan tool.
Diagnostic Aids
The vehicle may need to be driven to view full VES Commanded and Feedback Data parameters.
The numbers below refer to the step numbers on the diagnostic table.
- 2: 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: Tests if the resistance of the VES actuator is within specification.
- 7: 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 Variable Effort Steering Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Variable Effort Steering | |
| 2 | Install a scan tool. 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 amps | Go to Step 3 | Go to Step 4 |
| 3 | Using the scan tool, select F2: 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? | 5.7-7.2 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 (CTS) or Electronic Brake Control Module Replacement (CTS-V) . 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 Solenoid/Actuator Replacement . Did you complete the replacement? | Go to Step 15 | ||
| 15 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset? | Go to Step 2 | System OK | |
| IMPORTANT |
|---|
| Always perform the setup procedure for the EBCM. |
DTC C0450
Variable Effort Steering System Description and Operation
The Variable Effort Steering (VES) System varies the amount of effort to steer the vehicle as wheel speed changes or lateral acceleration occurs. The Electronic Brake Control Module (EBCM) controls an actuator located in the steering rack and pinion. The actuator consists of an electromagnetic coil and a pintle valve which moves in and out of the rack and pinion's input fluid orifice, regulating power steering fluid flow. The EBCM commands current from 0-1 amp to the VES actuator which varies the amount of effort to steer the vehicle. At low speeds, 1 amp of current is commanded to the VES actuator and the pintle valve is fully retracted which provides maximum fluid flow and maximum steering assist for easy turning and parking maneuvers. At high speeds, no current is commanded and the pintle valve moves closer to the orifice, decreasing fluid flow, providing firmer steering (road feel) and directional stability. The VES system uses the steering wheel position sensor input to calculate lateral acceleration during abrupt driving maneuvers. The system also uses the Antilock Brake System (ABS) wheel speed sensor inputs to determine vehicle speed. The EBCM is constantly monitoring these inputs to achieve the desired current to the VES actuator. The EBCM has the ability to detect malfunctions in the VES actuator or the circuits to the actuator. Any malfunctions detected will cause the VES outputs to be disabled and the EBCM will command the Driver Information Center (DIC) to display the SERVICE STEERING SYSTEM warning message via a class 2 serial data circuit.
See also:
• Scan Tool Does Not Power Up
• Diagnostic System Check - ABS
• Diagnostic Trouble Code (DTC) List
• Testing for Intermittent Conditions and Poor Connections
• Testing for Short to Ground
• Wiring Repairs
• Circuit Testing
• Connector Repairs
• Power Steering Gear Solenoid/Actuator Replacement
• Diagnostic System Check - Variable Effort Steering
• Diagnostic Trouble Code (DTC) List
• Steering Controls Connector End Views