System Description

WARNING: This page is about a different car, the 2004 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.

The rear window defogger system is controlled by BCM (Body Control Module) and IPDM E/R (Intelligent Power Distribution Module Engine Room).

The rear window defogger operates only for approximately 15 minutes.

Power is supplied at all times

through 20A fuse (No. 32, and 37, located in the IPDM E/R)
to rear window defogger relay terminals 3 and 6
through 50A fusible link [letter j, located in the fuse block (J/B)]
to BCM terminal 55.
With the ignition switch turned to ON or START position, Power is supplied
through 10A fuse [No.12, located in the fuse block (J/B)]
to rear window defogger relay terminal 1
through 10A fuse [No.1, located in the fuse block (J/B)]
to BCM terminal 38
through 10A fuse [No.2, located in the fuse block (J/B)]
to front air control terminal 14.
Ground is supplied
to BCM terminals 49 and 52
to front air control terminal 1
through body grounds M57, M61 and M79
to IPDM E/R terminals 38 and 60
through body grounds E15 and E24.
When front air control (rear window defogger switch) is turned to ON, Ground is supplied
to BCM terminal 9
through front air control terminal 11
through front air control terminal 1
through body grounds M57, M61 and M79.

Then rear window defogger switch is illuminated.

Then BCM recognizes that rear window defogger switch is turned to ON.

Then it sends rear window defogger switch signals to IPDM E/R and display control unit (with navigation) or display unit (without navigation) via DATA LINE (CAN H, CAN L).

When display control unit (with navigation) or display unit (without navigation) receives rear window defogger switch signals, and display on the screen.

When IPDM E/R receives rear window defogger switch signals,

Ground is supplied

to rear window defogger relay terminal 2
through IPDM E/R terminal 52
through IPDM E/R terminal 60
through body grounds E15 and E24

and then rear window defogger relay is energized.

With power and ground supplied, rear window defogger filaments heat and defog the rear window.

When rear window defogger relay is turned to ON, (with door mirror defogger) Power is supplied

through rear window defogger relay terminal 7
through fuse block (J/B) terminal 2Q
through 10A fuse [No. 8, located in the fuse block (J/B)]
through fuse block (J/B) terminal 5N.
to door mirror defogger (LH and RH) terminal 6.

Door mirror defogger (LH and RH) terminal 1 is grounded through body grounds M57, M61 and M79.

With power and ground supplied, rear window defogger filaments heat and defog the rear window and door mirror defogger filaments heat and defog the mirror.