Starting, function - GF07.10-P-1001OG

ENGINE 642.8 in MODEL 204

ENGINE 642.8 in MODEL 207 up to 5/31/13, 212, 218 up to model year 2014

Starting function requirements, general points

Circuit 87M ON (engine timing ON)
Engine OFF
Drive authorization system 3 (DAS 3) start enable
Engaged gear range "P" or "N" (on vehicles with automatic transmission)

Starting, general points

The starter control system in the CDI control unit (N3/9) is responsible for actuation and shutoff of the starter (M1).

For starting, the CDI control unit reads the following sensors and signals:

Oil temperature sensor (B1)
Rail pressure sensor (B4/6)
Atmospheric pressure sensor, for acquisition of the atmospheric pressure
Crankshaft Hall sensor (B70), for engine speed
Camshaft Hall sensor (B6/1)
Coolant temperature sensor (B11/4) (model 204, 207, 212), coolant temperature sensor (B11/4) (model 218)
Electronic ignition lock control unit (N73), "circuit 50 signal" via the chassis CAN (CAN E)
Fully integrated transmission control controller unit (Y3/8) (with code (427) 7-speed automatic transmission), gear range via the drive train CAN (CAN C)

The CDI control unit coordinates the injection sequence during starting based on the signals from the crankshaft Hall sensor and from the camshaft Hall sensor.

The CDI control unit actuates the following components to start the engine:

Starter
Pressure regulating valve (Y74)
Fuel injectors (Y76)
Quantity control valve (Y94)
Fuel pump (M3)

Fuel pump actuation

The fuel pump is actuated 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 the fuel pump is actuated directly and via the drive train CAN by the fuel system control unit (N118).

The start quantity control in the CDI control unit serves to calculate a specific start quantity at engine start irrespective of the position of the accelerator pedal sensor (B37).

Function sequence for start

The function sequence is subdivided into the following steps:

Function sequence for start begin
Function sequence for start end (with automatic transmission)
Function sequence for start end (with manual transmission)

Function sequence for start begin

When ignition key (transmitter key (A8/1)) is moved to the start position, the CDI control unit receives the "circuit 50 signal" from the electronic ignition lock control unit via the chassis CAN. The CDI control unit actuates the circuit 50 starter relay (N10/1kM) by means of a ground signal. The power contact on the starter relay closes and the starter solenoid switch is supplied at "circuit 50" with voltage from "circuit 30".

For vehicles with code (U42) BlueTEC (SCR) diesel exhaust treatment, no start enable is issued from the AdBlue® control unit (N118/5), if the AdBlue® tank is empty and the number of permissible engine starts with an empty AdBlue® tank is at zero.

If the CDI control unit detects that the engine is running via the crankshaft Hall sensor and the message "circuit 61 ON" and that the starting procedure has ended via the message "circuit 50 OFF", the driver will then be able to influence the injection quantity and thus the engine speed via the accelerator pedal sensor.

Function sequence for start end (with automatic transmission)

Starter control is carried out automatically by the CDI control unit (touch start). This means that once the start process is initiated, switching off "circuit 50" will have no further influence on the start procedure.

When the engine cranking speed has reached 400 to 700 RPM, or after a starting time of 5 to 40 s (dependent on coolant temperature), the CDI control unit interrupts the negative activation of the circuit 50 starter relay and thus terminates the starting procedure.

Function sequence for start end (with manual transmission)

On reaching an engine cranking speed of 400 to 700 RPM or upon disappearance of the "circuit 50 signal", the CDI control unit interrupts the negative activation to the circuit 50 starter relay and thus terminates the starting procedure.

If there is a repeat start after the end of the starting procedure, a waiting period of about 1.5 to 3 s is applied. This occurs in order to prevent meshing of the rotating pinion of the starter in the starter ring gear (ring gear protection).

Electrical function schematic for Start	MODEL 204	PE07.10-P-2701-97FAH
Electrical function schematic for Start	MODEL 207	PE07.10-P-2701-97EAF
Electrical function schematic for Start	MODEL 212	PE07.10-P-2701-97DAF
Electrical function schematic for Start	MODEL 218	PE07.10-P-2701-97XAA
Overview of system components for common rail diesel injection (CDI)		GF07.16-P-9997OG