Window Defogger Grid: Operation
A separate control circuit, connected to the heater control switch, operates the relay and timer. With the control switch on instrument panel and ignition switch "ON", the defogger relay contacts close. A timer, enclosed in relay case will allow the defogger to operate for about 8 to 12 minutes, depending upon ambient temperature, or until the control switch or ignition switch is turned "OFF". A pilot lamp on the instrument panel indicates when the system is in operation.
NOTE:
Defogger switch and electric tailgate switch are serviced as an assembly.