Starting System Operation

The illustration above is a simplified explanation of how the starting system operates in conjunction with the Body Processor Module (BPM) and the Engine Control Module (ECM).

Refer to the Starting Circuit Diagram in the Electrical Guide.

Ignition Switch to ON Position
When the ignition key is set to the normal run position, the following sequence occurs:
The isolation relay in each fusebox is energised to supply battery power to the fuses and associated circuits.
The BPM 'IGN ON' terminal is taken to 0V by the ignition switch.
The BPM checks that various parameters are correct e.g. - inertia switch is in the active condition transmission is in PARK - security system has been correctly disabled.

Ignition Switch at CRANK Position
When the ignition key is set to the crank position, the following sequence occurs:

The BPM 'CRANK SELECTED' terminal is taken to 0V by the ignition switch.

The BPM 'O/P ENGINE CRANK' terminal provides a path to ground for the starter relay coil, via Fuse 5 (10A) located in the under bonnet fusebox. This path to ground also indicates to the ECM 'l/P ENGINE CRANK' terminal, by taking it to 0V, that the engine has been requested to crank.

With the starter relay contacts closed, power via Fuse 3 (25A) in the engine management fusebox, is supplied to the pull-in winding of the starter solenoid.

The solenoid main contacts close and are held closed by the solenoid hold-in winding. Battery power is supplied to the starter motor through the solenoid main contacts, direct from the battery and the High Power Protection Module.