Control Assembly Test: Probe
- Turn ignition off. Unplug 10-pin and 14-pin interior fuse panel connectors. Remove DEFOG fuse from main fuse panel. Unplug connectors from defogger relay (located between front bumper and radiator) and defroster control panel. Check Black/White, Black/Yellow, and Black/Orange wires at fuse panel connectors for shorts to ground. Repair as necessary. Reconnect wiring to fuse panel. Install DEFOG fuse.
- Turn ignition on. Measure voltage at Black/Orange and Black/White wires at relay connector, and at Black/Yellow wire at defogger switch connector. See Fig 1 . If voltage at each wire is greater than 10 volts, go to next step. If voltage at any wire is less than 10 volts, repair appropriate wire.
- Turn ignition off. Reconnect switch and defroster relay. Turn ignition on. Press switch. Backprobe Black/Blue wire at defroster relay. If battery voltage does not exist, go to next step. If battery voltage exists, go to step 7).
- Turn ignition off. Unplug switch connector. Measure resistance of Black wire between switch connector and ground. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair Black wire.
- Turn ignition off. Unplug connectors from defroster relay and switch. Measure resistance of Purple wire between relay connector and switch connector. Measure resistance of Purple wire between relay connector and ground. Resistance between relay connector and switch connector should be less than 5 ohms. Resistance between relay connector and ground should be greater than 10,000 ohms. If resistance is as specified, go to next step. If resistance is not as specified, repair Purple wire.
- Measure resistance between relay contacts (Black/Orange and Black/Blue wires on mating connector). Apply 12 volts to relay coil terminals (Black/White and Purple wires on mating connector). If resistance is less than 5 ohms with 12 volts applied to coil, and greater than 10,000 ohms with no voltage applied, go to next step. If resistance is not as specified, replace relay.
- Unplug rear window connector. Turn ignition on. Press rear window defogger switch. Measure voltage between Black/Blue wire at connector and ground. If battery voltage exists, go to next step. If battery voltage does not exist, repair Black/Blue wire between connector and relay.
- Turn ignition off. Remove ROOM fuse. Measure resistance between Black wire at rear window connector and ground. If resistance is not less than 5 ohms, repair Black wire to ground. If resistance is less than 5 ohms, repair or replace rear window. See GRID FILAMENT TEST under TESTING. See GRID FILAMENT REPAIR under ON-VEHICLE SERVICE.