Electrical Power Steering Module (EPS)
- Control module with power stage
- Pump motor
- Pump
- Terminal for 15 supply and CAN
- Terminal for power supply (30 supply) and ground.
The electrical power steering module (EPS) consists of one unit with the following main components:
- control module
- pump motor
- pump.
The electrical power steering module (EPS) is under the right-hand headlamp. The electrical power steering module (EPS) can only be replaced as one unit. The control module, pump motor and pump cannot be replaced as separate components.
When replacing the electrical power steering module (EPS), the vehicle must be configured with new software to match the profile of the car.
Control module
The control module is built into the pump motor casing. All the electrical terminals are on the top of the control module. The control module has logics for all functions which enables it to read, write and store software and diagnostic trouble codes (DTCs). The control module also manages all communication with the other control modules via the controller area network (CAN).
The control module contains a number of power stages, field effect transistors (FET). The field effect transistors control the output of the pump motor upon request from the control module. The control module also has a built-in NTC temperature sensor (low temperature results in high resistance, high temperature in low resistance). This allows the control module to diagnose, limit or disengage the power steering if an excessive temperature is registered or there are other faults in the control module.
Hydraulic pump (pump/pump motor)
The hydraulic pump consists of a pump and a pump motor. The pump is in an oil reservoir. The pump motor, which drives the pump, is under the reservoir. The pump motor is a brushless DC motor. The pump motor also has Hall sensors. The Hall sensor provide the control module with information about the speed of the pump motor, and therefore the prevailing hydraulic pressure (which is indirectly speed dependent). This allows the control module to control and diagnose the pump motor.