Description And Operation
DESCRIPTION
The airbag system is a sensitive, complex electro-mechanical unit. Before attempting to diagnose, remove or install the airbag system components you must first disconnect and isolate the battery negative (ground) cable. Then wait two minutes for the system capacitor to discharge. Failure to do so could result in accidental deployment of the airbag and possible personal injury. The fasteners, screws, and bolts, originally used for the airbag components, have special coatings and are specifically designed for the airbag system. They must never be replaced with any substitutes. Anytime a new fastener is needed, replace with the correct fasteners provided in the service package or fasteners listed in the parts books.
The steering column contains the following modules, switches and components:
| 1. | Steering Wheel |
| 2. | Driver AirBag (DAB) |
| 3. | Electronic Vehicle Information Center (EVIC) Switch |
| 4. | Remote Radio Switches |
| 5. | Steering Column Control Module (SCCM) |
| 6. | Steering Column Adjustment Locking/Unlocking Lever |
| 7. | Electric Power Steering (EPS) Motor |
| 8. | Intermediate Shaft |
| 9. | EPS Module |
| 10. | Speed Control Switch |
Electric Power Steering (EPS)
The EPS motor, which includes the upper steering column, and EPS module are serviced as an assembly and are not available as individual components.
The vehicle features EPS. Since the steering system is fully electric, all power assistance is provided by an electric motor system.
The EPS system is a power steering system designed to reduce the force necessary for maneuvering the vehicle at low speed, without rendering steering too light at higher speeds. EPS provides:
- A lighter and less complex system with fewer components.
- Less noise and improved driving comfort.
- Power assistance relative to vehicle speed.
- Improves fuel economy as there is no power drain from a power steering pump.
- Allows optimal tuning of feedback to the driver.
The speed-sensitive, variable power assistance responds to sensors monitoring steering torque, steering wheel speed and angle, and vehicle speed. The steering system is fully integrated with the electronic stability control system and helps compensate in situations where the wheels have different grip.
For additional information about the EPS module. Refer to MODULE, ELECTRIC POWER STEERING (EPS), DESCRIPTION AND OPERATION .
For additional information about the SCCM. Refer to MODULE, STEERING COLUMN CONTROL (SCCM), DESCRIPTION AND OPERATION .
For additional information about the other components, switches and modules contained in the steering column, refer to the Service Infromation that covers that component.
OPERATION
The EPS system operates according to the operating information received by the Controller Area Network (CAN), such as:
- Vehicle speed
- Engine speed
- Ignition status
The EPS assembly includes two built-in sensors that provide:
- Steering angle
- Steering wheel torque (driver input)
The system will turn off power assistance if the following criteria are met:
- Engine speed is less than 600 rpm
- Ignition is in the OFF position
This allows the system to continue providing assistance in the event of a stall or a condition where ignition input is lost due to an electrical fault.
Safety goggles should be worn at all times when working on steering columns.
To service the steering wheel, switches or airbag, refer to the appropriate diagnostic information, and follow all WARNINGS and CAUTIONS.