Starter control function

L15.30-0003-76

Vehicles without automatic transmission or automatic clutch

B11/4 Coolant temperature sensor

CAN Controller Area Network (CAN databus)

K6 Starter relay

L5 Crankshaft position sensor

M1 Diesel starter

N3/9 CR control module

N15/4 Automatic clutch control module

S2 Starter switch

Y3/7n2 Front transmission control (FTC) control module

Key positions:

0 The key can be withdrawn only in position 0

1 The majority of electrical consumers can be switched on

2 Preglowing and driving position

3 Start position

Task

 Initiating the engine start process (starter ON)

Function

When the key in the start switch (S2) is turned into the start position, circuit 50 is switched to the engine control module. The starter (M1) is actuated by the engine control module through the starter relay (K6).

Conditions for starter ON:

 Drive authorization system deactivated (circuit 15U enabled)

 Key in start position

 Engine speed = 0

The values for the start protection and the ring gear protection are stored in the control module.

Conditions for starter OFF:

 Key not in start position (start operation ended)

or  maximum permissible engine speed (approx. 1000 rpm) is exceeded once (start protection)

In the case of a repeat start, there is a blocking period of 1.5 seconds after the starter is switched off in order to prevent the starter meshing with the starter ring gear of the engine when the starter pinion is still rotating (ring gear protection).

Safety precautions in the event of a fault:

In the event of an engine start without a start signal (circuit 50 not connected), caused by faulty mechanisms, fuel injection is not enabled in order to prevent the engine from starting.

Exception: Fuel injection is enabled from a vehicle speed of  2.4 km/h even without a start signal in order to enable the vehicle to be push-started.