Ignition Switch: Description and Operation

Ignition Switch Unit (20)

Principal use
The ignition switch (ISM) is linked with the column integration module (CIM) and the steering column lock (SCL) and has the following uses:
- Send the transponder code to CIM via the communication cable for identification.
- Send the key position to CIM via the communication cable for forwarding to the buses.
- Send the remote control battery status to CIM via the communication cable in order to display a battery warning on SID.
- Prevent the key being turned from LOCK to OFF before the transponder code has be approved and SCL unlocked.
- Prevent the key being turned from OFF to LOCK before the car has stopped and the selector lever has been moved to P (aut).
- Release the SCL locking pin via a direct lead prior to locking the steering column after a command on the communication cable from CIM.
- Find out via a direct lead from SCL that the locking pin is in unlocked and released position and send it to CIM on the communication cable.
- Illuminate the key positions.
- Provide a number of units with battery voltage via a direct lead in certain key positions.

Type
ISM is a unit that contains the following components:







- Ignition switch with four positions, LOCK, OFF, ON and ST, and a switch to indicate that the key is inserted.
- Microprocessor
- Solenoid to prevent the key from being turned from LOCK to OFF and from OFF to LOCK.
- Transponder antenna for identifying the key transponder.
- Illumination for key positions.

Connection


















Output +X, T8