OPERATION PROCEDURE
- Connect both battery cables. NOTE: Supply power using jumper cables if battery is discharged.
- Use the Intelligent Key or mechanical key to turn the ignition switch to the "ACC" position. At this time, the steering lock will be released.
- Disconnect both battery cables. The steering lock will remain released and the steering wheel can be rotated.
- Perform the necessary repair operation.
- When the repair work is completed, return the ignition switch to the "LOCK" position before connecting the battery cables. (At this time, the steering lock mechanism will engage.)
- Perform a self-diagnosis check of all control units using CONSULT-III.
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- EPS control unit performs an arithmetical operation on data, such as steering wheel turning force (sensor signal) from the torque sensor, vehicle speed signal, etc. Then it generates an optimum assist torque to the EPS motor according to the driving condition.
- EPS control unit decreases the output to EPS motor while extremely using the power steering function (e.g., full steering) for protecting EPS motor and EPS control unit (Protect overload status). While activating protect overload status, the assist torque gradually decreases, and the steering wheel turning force becomes heavy. The normal assist torque reactivates by not steering.
- In case of an error in the electrical system, the fail-safe function stops output signals to the EPS motor. Then the previous state is changed to the manual steering state.
- Self-diagnosis can be done with CONSULT-III.
COMPONENTS FUNCTION DESCRIPTION
| Component parts | Function |
|---|---|
| EPS control unit (Electric power steering control unit) | Outputs optimum assist torque signal to EPS motor. Reduces output signals to EPS motor and protects EPS motor and EPS control unit when using power steering continuously and excessively. As a fail-safe function, turned off output signal to EPS motor and then enters a manual steering state, if malfunction is detected in EPS system. |
| EPS motor | Products assist torque by control signal from EPS control unit. |
| Torque sensor | Detects steering wheel turning force and outputs sensor signal to EPS control unit. |
| Reduction gear | Increases motor-produced assist torque by worm gear and transmits it to column shaft. |
| EPS warning lamp | Illuminates if malfunction is detected in electrical system of EPS system. |
| ECM | Transmits the following signals via CAN communication to EPS control unit. Engine status signal |
| ABS actuator and electric unit (control unit) (With ABS) | Transmits the following signals via CAN communication to EPS control unit. Vehicle speed signal |
| Combination meter | Transmits the following signals via CAN communication to EPS control unit. Vehicle speed signal |
| TCM (Without ABS) | Transmits the following signals via CAN communication to EPS control unit. Vehicle speed signal |
COMPONENTS FUNCTION DESCRIPTION
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.
For details, refer to " CAN SYSTEM SPECIFICATION CHART ".
Fail-Safe Function
- If any malfunction occurs in the system, and control unit detects the malfunction, EPS warning lamp on combination meter turns ON to indicate system malfunction.
- When EPS warning lamp is ON, enters a manual steering state. (Control turning force steering wheel becomes heavy.)
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- To perform trouble diagnosis, it is a must to have an understanding about vehicle systems (control and mechanism) thoroughly.
- It is also important to clarify customer complaints before starting the inspection. First of all, reproduce the symptoms, and understand them fully. Ask customer about his/her complaints carefully. In some cases, it will be necessary to check symptoms by driving vehicle with customer. CAUTION: Customers are not professionals. It is dangerous to make an easy guess like "maybe the customer means that..." or "maybe the customer mentions this symptom".
- It is essential to check symptoms right from the beginning in order to repair malfunctions completely. For intermittent malfunctions, reproduce symptoms based on interview with customer and past examples. Do not perform inspection on ad hoc basis. Most intermittent malfunctions are caused by poor contacts. In this case, it will be effective to shake suspected harness or connector by hand. When repairing without any symptom diagnosis, you cannot judge if malfunctions has actually been eliminated.