Steering (Operation): Description and operation (page 3 of 3)

When the ignition is switched on, the EPAS ECU performs a start-up (diagnostic) check procedure. The ECU illuminates the EPAS fault warning lamp in the instrument pack. The lamp will remain illuminated until the engine is started and the ECU receives an engine running signal from the crankshaft position (CKP) sensor.

The inputs from the torque sensor, CKP sensor (engine running signal) and road speed transducer are passed to the ECU and, via the interface, to the main control computer.

The computer processes the data and calculates the required steering assistance and outputs the required current to the motor. The motor then operates to apply torque via the worm gear in the required direction to the worm wheel.