Diesel – circuit operation

DIESEL – CIRCUIT OPERATION

Fuel Quantity Actuator

Once again located within the injection pump, this is a moving magnet actuator, failure of which will cause the engine to stall or not start as the ECM (Z132) will activate the Fuel Shut-Off Solenoid (K111).

Injection Timing (Solenoid Valve Injection Timing Device (K229))

This is another actuator within the injection pump. The ECM (Z132) receives a signal from the needle lift sensor and attempts to correct the injection timing accordingly. If a change does not occur, then the ECM (Z132) assumes a fault exists, activates the warning lamp and reduces the quantity of injected fuel.

Fuel Shut-Off Solenoid (K111)

The Fuel Shut-Off Solenoid (K111) shuts the engine down if the ECM (Z132) detects a major fault. Failure of the valve itself does not activate the warning lamp, although if a short circuit occurs, the engine will shut down.

Cruise Control

Due to the DDE system being
drive by wire’, a cruise control feature is supplied in the ECM (Z132) itself. Activation is via the steering wheel switches to a converter box and on a single line to the ECM (Z132). Failure of the signal results in cruise control not working.

Brake Switches

The ECM (Z132) has two brake inputs, each of opposite polarity. Comparison of the polarity states provides the ECM (Z132) with a brake sense (i.e. if switch 1 high and switch 2 low going to switch 1 low and switch 2 high) and so cancels cruise control. If both switches are the same polarity, the ECM (Z132) senses a fault and does not allow cruise control.

Vehicle Speed Signal

The ECM (Z132) takes this signal from the Anti-Lock Brake System ECU (Z108) and uses the information for cruise control and
active surge damping’. Failure of the signal results in cruise disallowed and temporary lack of surge damping (i.e. hard acceleration will cause the vehicle to surge slightly). After 10 sec. a substitute value of 150 km/h

is used. Surging will reduce so as to be hardly noticeable.

Theft Alarm

The ECM (Z132) has a simple on/off input regarding the theft alarm. The ECM (Z132) will not allow the engine to start once activated and will kill the engine if activated up to 300 RPM (programmable). Over 300 RPM, the engine is unaffected.

Relays

The DDE engine management system on the diesel vehicles uses four relays: ECM (Z132) power supply (main relay), glow plug relay, starter motor relay and fuel pump relay. Two are located in the fuse box and two in the ECM (Z132) box behind the battery.