Voltage is applied at all times from the DEFOG/SEATS CKT BRKR 12, circuit 1240, to the rear defogger timer/relay. When the ignition switch is turned to the RUN position voltage is appplied by the HVAC Fuse 6, circuit 241, to the rear defogger switch and the rear defogger timer/relay. Ground is provided at all times to the rear defogger switch and the rear defogger timer/relay through G200, circuit 650.

Rear Defogger Operation

When the rear defogger switch is pressed, voltage is momentarily applied to the solid state device within the rear defogger timer/relay through circuit 292. Along with this, voltage is also supplied through circuit 241 and ground through circuit 650 to the solid state device. When all three of these inputs occur the solid state device provides a ground to the solenoid within the rear defogger timer/relay. Voltage is supplied at all times to the solenoid through the DEFOG/SEATS CKT BRKR 12, circuit 1240. When the ground is applied to the solenoid the switch contact within the rear defogger timer/relay closes providing voltage to the rear defogger grid through circuit 293. The rear defogger grid receives ground at all times through G310, circuit 1150 (coupe) or G320, circuit 1750 (convertible). When the rear defogger grid receives voltage through circuit 293 the rear defogger operates.

The rear defogger timer/relay contains an internal timer in order to control the time the internal contacts are closed. The defog cycle lasts 10 minutes when the ignition switch is turned to the RUN position and the rear defogger switch is pressed for the first time.

When the rear defogger switch is pressed again after the 10 minute time out, the rear defogger will run in a 5 minute defog cycle. This rear defogger will run at 5 minute cycles each time the rear defogger switch is pressed until the ignition switch is turned to the OFF position and then back to the RUN position. The defog cycle will then reset to the original 10 minutes.

Rear Defogger On Indicator

Ground is always supplied to the rear defogger switch on indicator through G200 circuit 650. When the switch contact within the rear defogger timer/relay closes voltage is not only provided to the rear defogger grid through circuit 293, but to the on indicator in the rear defogger switch. When this voltage is applied the indicator turns on and stays on until the rear defogger is shut off or turns off after the 10 minute cycle. The indicator will turn and remain on as long as the rear defogger is running. The on indicator turns off when the rear defogger turns off.