The rear defogger system consists of the following components:

When you turn on the rear defogger, the IPC confirms that the engine is running. The IPC receives the engine status from the powertrain control module (PCM) thorough the class 2 serial data line. When the IPC confirms the engine status, the IPC turns on the defogger-ON LED. The IPC commands the PZM to turn on the defoggers through the class 2 serial data line. When the PZM receives the command, the defogger relay coil grounds through the PZM terminal C2.

The IPC also controls the timing cycle function. When the 5-10 minute cycle has elapsed, the IPC turns off the defogger-ON LED. Through the class 2 serial data line, the IPC commands the PZM to turn off the defoggers. When the PZM receives the command, the ground is removed through the PZM terminal C2.

When the PZM grounds the defogger relay coil, the relay energizes, which closes the relay contacts. Battery voltage from the BODY 2 fuse is available to the HTD MIR fuse and the RR DEFOG fuse. The HTD MIR fuse provides battery voltage to the outside mirror defoggers. The RR DEFOG fuse provides battery voltage to the rear window defogger grid.