Chart 7 Defogger: Rear Window, Outside Mirrors on Continuously

CIRCUIT OPERATION
The Rear defogger system consists of defogger relay, rear defogger grid, body control module, outside mirror defoggers, instrument panel cluster and related fuses and wiring.

Instrument Panel Cluster (IPC) and Body Control Module (PZM)
When the rear defogger is turned ON, the IPC confirms that the engine is running. The IPC receives engine status from the PCM via the serial data line. When engine status has been confirmed, the IPC turns ON the defogger-ON LED and commands the PZM to turn ON the defoggers via the data line. When the PZM receives the command, the defogger relay coil grounds through PZM terminal C2.

IPC also controls the timing cycle function. when the 5 or 10 minute cycle has elapsed, the IPC switches OFF the defogger-ON LED and commands the PZM to turn OFF defoggers, via the data line. when the PZM receives the command, ground is removed through PZM terminal C2.

Defogger Relay and Defogger
When the PZM grounds the Defogger Relay coil, the relay energizes causing the relay contacts to close. Battery voltage from Maxi Body 2(R) is applied to trunk compartment fuse block and the HTD MIR and REAR DEFOG fuses. The HTD MIR Fuse provides battery voltage for the outside mirror defoggers. The REAR DEFOG Fuse provides battery voltage for the rear window defogger grid.