Ignition Off, Function - GF07.10-D-1002TSA

Engine 651.9 in model 907 

Block diagram 

Function requirements for ignition OFF, general points 

• Circuit 87M ON (Engine management ON)
• Circuit 15 on

Ignition OFF, general points 

For ignition OFF, the engine is first switched off and then the engine management in the CDI control unit is switched off.

Function sequence for ignition OFF 

For ignition OFF, the electronic ignition lock (EZS) control unit switches off relay 1 circuit 15 (F152kA).

If the CDI control unit receives the "circuit 15 OFF signal via the circuit 15" relay, the following component parts are switched off and the computer run-on is started:

• Pressure regulator valve
• Fuel injectors
• Quantity control valve
• Fuel pump with fill level sensor via the fuel pump control unit

During power-down of the control unit, the residual AdBlue® reducing agent is pumped out of the pressure line by the AdBlue® delivery pump through the AdBlue® extraction pump which is actuated by the AdBlue® control unit. The AdBlue® metering valve is opened at the same time so that no vacuum arises in the AdBlue® pressure line. The duration of the run-on and the point in time at which the reduction agent is pumped back depends on the exhaust gas temperature. This is recorded by the temperature sensor upstream of the SCR catalytic converter because if the exhaust gas is too hot, damage may occur to the AdBlue® pressure line and the other system components.

The computer run-on is determined by the CDI control unit and is approx. 4 s. However, it may also last for several minutes due to various functions (for example, on-board diagnosis (EOBD), drive authorization system 4 (FBS 4), thermal management). When the computer run-on is complete, the circuit relay 87Mis switched off and the engine management is disconnected from the onboard electrical system (switched off) as a result.

System tests are conducted by the CDI control unit during the processor run-on period and the fault memory is updated.