51

Pump motor locked or open circuit.

Always ON

Malfunction in ECU.

Fail-Safe

In the event of a malfunction in an input signal to the ECU, the ECU cuts off its current to the actuator. As a result, the brake system operates in the same way as in a vehicle without ABS, and normal braking function is assured.

Fig. 6.21 Self-diagnosis data from an ABS computer

2. The cam rotates and the pump plunger covers the feed port. The spill valve remains open and the injector valve is still on its seat.

3. Further rotation of the cam pushes the plunger towards the end of its stroke. The colenoid now closes the spill valve. This causes the high pressure fuel to lift the injector valve from its seat and injection takes place.

4. The plunger has now reached the end of its stroke. The colenoid has opened the spill valve and the injection process is completed.

Fig. 6.22 Test result from a circuit that includes a clamping diode

The commencement and ending of injection can be varied by the computer control of the colenoid and spill valve.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

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