Ignition Switch (ISM), Brief Description

Ignition Switch (ISM), Brief Description

Overview
^ Key/Remote control
^ Ignition switch, ISM (20)
^ Steering column lock, SCL (708)
^ Column integration module, CIM (703)
^ Engine Control Module (ECM)
^ Main instrument unit, MIU (540)

Description

Inserting the key in the ignition switch will wake up the column integration module (CIM) and unlock the steering column. The key can then be turned past LOCK to OFF and then to ON and ST. The key is blocked mechanically so that it can only be removed in LOCK position.

As soon as the key is inserted the ignition switch (ISM) will continuously send key position to the CIM. The CIM then conveys key position to the P and I-bus. The engine control module (ECM) is responsible for the starter motor being activated in ST position.