System Description

WARNING: This page is about a different car, the 2003 Nissan Murano. 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 at all times supplied

through 20A fuse [No. 77, and 78, located in the IPDM E/R]
to rear window defogger relay terminals 3 and 6.
through 15A fuse [No. 28, located in the fuse block (J/B)]
to A/C and AV switch terminal 1.
through 50A fusible link [letter F, located in the fuse block (J/B)]
to BCM terminal 7.

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 35.
through 10A fuse [No. 6, located in the fuse block (J/B)]
to A/C and AV switch terminal 2.

Ground is supplied

to BCM terminal 8
through body grounds E13, E26 and E28.
to A/C and AV switch terminal 5
through body grounds M14 and M78.
to internal CPU of IPDM E/R terminals 14 and 45
through body grounds E13, E26 and E28.

When A/C and AV switch (rear window defogger switch) is turned to ON, Ground is supplied

to BCM terminal 69
through A/C and AV switch terminal 16
through A/C and AV switch terminal 5
through body grounds M14 and M78.

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 54,
through internal CPU of IPDM E/R and IPDM E/R terminal 45.
through body grounds E13, E26 and E28,

and then rear window defogger relay is energized.

When rear window defogger relay is turned ON,

Signals are transmitted,

through rear window defogger relay terminals 5
to rear window defogger terminal 1,
Rear window defogger terminal 2, is grounded through body grounds B7 and B20.

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 terminals 5 and 7,
through fuse block (J/B) terminal 2C,
through 10A fuse [No. 8, located in the fuse block (J/B)],
through fuse block (J/B) terminal 5B.
to door mirror defogger (Driver side and passenger side) terminal 1.

Door mirror defogger (Driver side and passenger side) terminal 5 is grounded through body grounds M14 and M78.

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.