Ignition Key Interlock

On vehicles equipped with the interlock safety feature, the vehicle must be in park and the transfer case in high or low gear before the key can be removed from the ignition. If the gear selector or transfer gear is out of gear, the key must be cycled before removal.

If the vehicle is not in park, voltage from Fuse F12 is applied to the Key Barrel Switch (X230) through the closed contacts of the Transmission flange Selector Switch (Z110). When the ignition switch is placed in the 0 position, the Key Barrel Switch (X230) closes to energise the solenoid and prevent key removal.

If the key is in the ignition and the transfer box is in the neutral position, Interlock Relay 1 (K153) is de-energised since the relay coil is not grounded by the Transfer Box Position Switch (X175). When the relay is de-energised, voltage is applied to the Key Barrel Switch (X230) through the relay's switch contacts and the Key-In Switch (X229) causing the solenoid to energise and prevent key removal.

If the Transfer Box is in the "H" or "L" position, the Interlock Relay 1 (K153) is energised, since the relay coil is grounded by the Transfer Box Position Switch (X175). When the relay is energised, voltage to the Key Barrel Switch (X230) is interrupted. If the vehicle is in Park the Transmission Range Selector Switch (Z110) contacts are open. When the switch contacts are open, voltage to the Key Barrel Switch (X230) is also interrupted. The Ignition Key Lock Solenoid (K191) is then disabled, allowing removal of the key.