Differential Lock Circuit Description

Differential Lock Circuit Description

The differential lock system has an electrical circuit that lets the driver know when the differential lock is engaged by means of an indicator lamp on the instrument panel cluster. The main components of the system are air pressure-operated and related.

The air pressure-operated, differential lock switch is normally in the open position. When the ignition switch is in the START position, current will flow through the differential lock indicator lamp in the IP cluster, through a diode in the IP, and then grounded through the ignition switch. The differential indicator lamp will go ON and then go OFF as the ignition switch is released from START to the RUN position.This lets the driver know that the indicator lamp is functioning properly. When the differential lock switch(actually an air valve) is switched to the ON position, this will cause air pressure to build and close the differential lock switch(valve), this will allow current to flow through the switch to chassis ground and cause the differential lock indicator lamp to come ON in the IP cluster.

Press the differential lock switch a second time in order to disengage the differential lock, and to turn OFF the differential lock indicator lamp.