Ignition OFF, function - GF07.10-P-1002OG

ENGINES 642.8 in MODEL 204.0/2/9, 207.3/4, 212.0/2, 218 

Function requirements for ignition OFF, general points 

• Circuit 87M ON (engine control ON)
• Circuit 15 ON

Ignition OFF, general points 

When the ignition is switched off, first the engine and then the CDI engine control unit (N3/9) are switched off.

Function sequence for ignition OFF 

When the ignition is switched off, the electronic ignition lock control unit (N73) switches off the circuit 15 relay (N10/1kJ) via the chassis CAN (CAN E).

If the CDI control unit receives the signal "circuit 15 OFF" via the circuit 15 relay, the following components will be switched off and the computer run-on started:

• Fuel pump (M3) (on model 207.3 up to 11/2009 and on model 212.0 up to 08/2009 via the fuel pump relay (N10/2kD). On model 204, model 207.3 as of 12/2009, model 207.4, model 212.0 as of 09/2009, model 212.2, model 218 by the fuel system control unit (N118))
• Fuel injectors (Y76)
• Pressure regulating valve (Y74)
• Quantity control valve (Y94)

For vehicles with code (U42) BlueTEC (SCR) diesel exhaust treatment, the run-on period of the AdBlue® control unit (N118/5) is started. During the control unit run-on period, the remaining AdBlue® reducing agent is suctioned out of the AdBlue® pressure line. The AdBlue® metering valve (Y129) is opened at the same time so that no vacuum arises in the AdBlue® pressure line. The duration of the run-on period and the timing of reducing agent return are dependent on the exhaust temperature as detected by the temperature sensor upstream of the SCR catalytic converter (B16/15), since excessively hot exhaust can damage the AdBlue® pressure line and other system components.

The computer run-on period is determined by the CDI control unit and lasts about 4 s. It can, however, last for several minutes due to various functions (such as On-board Diagnosis (OBD), Drive Authorization System (DAS), thermal management).

When computer run-on is complete, the engine circuit 87 relay (N10/1kN) is switched off and the engine control system is disconnected from the vehicle electrical system (switched off).

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

The "circuit 31" ground connection is made from the on-board electrical system battery (G1) via the front right ground point battery (W10) and via multiple ground lines to the electronics ground point Left major assembly compartment (W16/5).

When the ignition is OFF, the CDI control unit is supplied with power from the on-board electrical system battery via "circuit 30 fused".

	Electrical function diagram for ignition OFF	Model 204	PE07.10-P-2702-97FAH
		Model 207	PE07.10-P-2702-97EAF
		Model 212	PE07.10-P-2702-97DAF
		Model 218	PE07.10-P-2702-97XAA
	Overview of system components for common rail diesel injection (CDI)		GF07.16-P-9997OG