Ignition On, Function - GF07.10-D-1000TSC

Engine 642.8 in model 907 

Block diagram 

Function requirements for ignition ON, general points 

• Chassis 30

Ignition ON, general points 

For ignition ON, the engine management in the CDI control unit is switched on and the engine is prepared for starting.

Function sequence for ignition ON 

When switching on the ignition, the on-board electrical system voltage is passed on from "circuit 30" to "circuit 15" by the EZS control unit. If a voltage applies at "circuit 15" of the CDI control unit, the relay at circuit 87M (F152kD) is actuated with a ground signal. This causes the relay to close its power contact and, according to the corresponding fuses, the "circuit 30" voltage is passed on as "circuit 87" to the CDI control unit and to the corresponding sensors and actuators of the engine management.

If voltage is present at "circuit 87", the engine management switches on and an output stage driver in the CDI control unit takes over the further actuation of circuit relay 87M (F152kD).

When the engine management is switched on, the CDI control unit carries out the following functions:

• For complete security, the fuel pump with the fill level sensor is actuated via the fuel pump control unit (only the first time the ignition is switched ON after the vehicle is unlocked).
• In the instrument cluster, the engine diagnosis indicator lamp is actuated by the CDI control unit for monitoring.
• Data exchange with the EZS control unit (circuit 50 and drive authorization signal).
• Actuation of the glow output stage. The glow output stage responds by actuating the glow plugs on the positive side. At the same time, the preglow indicator lamp (A1e16) in the instrument cluster is actuated.
• The fault memory in the CDI control unit can be read out and deleted with XENTRY Diagnostics via the diagnostics connection.
• A diagnosis can be carried out with XENTRY Diagnostics via the diagnostics CAN and via diagnostics connection.
• The throttle valve actuator checks its return spring (by the position of the throttle valve) and adjusts the position of the actuator as necessary.