XC70 AWD L6-3.2L VIN 98 B6324S (2009)
Engine Control Module: Description and Operation
Function
Part 1
Function
Start
The starter motor (6/25) is supplied with power via the starter motor relay (2/35), the starter motor relay is controlled by the engine control module
(ECM) (4/46).
The start process is as follows:
1. The starter button on the Start control module (SCU) is pressed (position III).
2. A high signal (Ubat) from the start control module (SCU) (3/132) reaches the central electronic module (CEM) via LIN communication.
3. The central electronic module (CEM) (4/56) uses the button signal together with the signal from the brake light switch (3/9) and creates a start
request that is transmitted to the engine control module (ECM) via CAN communication.
4. Based on the start request and the directly connected signal from the start control module (SCU), the engine control module (ECM) activates the
starter motor solenoid by grounding and supplying power to the starter motor relay coil.
5. The relay closes the circuit between the starter motor solenoid and the fuse in the relay/fuse box in the engine compartment, activating the starter
motor.
6. The engine control module (ECM) activates the starter motor until the engine starts (the engine speed (rpm) exceeds a certain value)
Auto start
If the starter button is released before the engine is started, the starter motor continues to run. The starter motor runs until the engine is started or until
after a certain amount of time, depending on the engine coolant temperature (ECT). Low temperatures permit longer start times.
If the engine does not turn or if the engine speed is extremely low when the start relay is activated, the engine control module (ECM) interrupts start
relay activation.
Activation of the starter motor is not permitted or is interrupted if:
-
the engine is running (the engine speed (RPM) above a certain value)
-
the immobilizer function does not allow a start. For further information also see Design and Function, Immobilizer
-
the gear selector is not in position "P" or "N". The engine control module (ECM) receives a signal indicating the position of the gear selector (P/N
engage/disengaged) from the transmission control module (TCM) (4/28), partially via the controller area network (CAN) and partially via a
