Component Description
| Components parts | Reference |
|---|---|
| EPS control unit | " EPS CONTROL UNIT " |
| EPS motor | " EPS MOTOR " |
| Torque sensor | " TORQUE SENSOR " |
| Reduction gear | " REDUCTION GEAR " |
| EPS warning lamp | " EPS SYSTEM: SYSTEM DESCRIPTION " |
| ECM | Transmits mainly the following signals to EPS control unit via CAN communication. Engine status signal |
| ABS actuator and electric unit (control unit) | Transmits mainly the following signal to EPS control unit via CAN communication. Vehicle speed signal (ABS) |
| Combination meter | Transmits mainly the following signal to EPS control unit via CAN communication. Vehicle speed signal (METER) Turns ON the EPS warning lamp according to the signal from EPS control unit via CAN communication. |
EPS SYSTEM: System Description
- 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 signal to the EPS motor according to the driving condition.
- In case of an error in the electrical system, the fail-safe function stops output signals to the EPS motor. Refer to " «EPS SYSTEM: FAIL-SAFE»(ref-605975-S14083273632014032500000) ".
- EPS control unit decreases the output signal to EPS motor while extremely using the power steering function (e.g., full steering) consecutively for protecting EPS motor and EPS control unit (Overload protection control). Refer to " «EPS SYSTEM: PROTECTION FUNCTION»(ref-605975-S09016957492014032500000) ".
- Extensive steering at low speed will cause the ECU and MOTOR to heat up, once temperature reaches critical point ECU will reduce current to reduce heat up. System will recover as temperature lowers (reduced or no assistance).
Scheme 1
ECU IDENTIFICATION
Displays the part number stored in the control unit.
Description
- In general, customers have their own criteria for a problem. Therefore, it is important to understand the symptom and status well enough by asking the customer about his/her concerns carefully. To systemize all the information for the diagnosis, prepare the interview sheet referring to the interview points.
- In some cases, multiple conditions that appear simultaneously may cause a DTC to be detected.
Scheme 2
EPS control unit receives the vehicle speed signal from ABS actuator and electric unit (control unit) via CAN communication line.
EPS control unit receives the engine status signal from ECM via CAN communication line.
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 communicate data but selectively reads required data only.
EPS warning lamp does not turn ON when turning ignition switch ON from OFF. (Check the illumination of the EPS warning lamp.)
EPS warning lamp does not turn OFF several seconds after engine started.
Steering wheel turning force is heavy or light.
Unbalance steering wheel turning force and return between right and left.
Unbalance steering wheel turning force (torque variation).