System Description

WARNING: This page is about a different car, the 2008 Nissan Maxima. 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 fuses (No. 32, and 37, located in the IPDM E/R)
To rear window defogger relay terminals 3 and 6
Through 50A fusible link (letter f , located in the fuse and fusible link box)
To BCM terminal 70.

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
To unified meter and A/C amp. terminal 22
Through 10A fuse [No. 1, located in the fuse block (J/B)]
To BCM terminal 38.

Ground is supplied

To BCM terminal 67
To unified meter and A/C amp. terminals 29 and 30
Through body grounds M57, M61 and M79
To IPDM E/R terminals 38 and 60
Through body grounds E15 and E24.

When unified meter and A/C amp. (rear window defogger switch) is turned to ON, ground is supplied

To BCM terminal 9
Through unified meter and A/C amp. terminal 38
Through unified meter and A/C amp. terminal 29 and 30
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) via CAN communication (CAN-H, CAN-L) or A/C display (without navigation).

When display control unit (with navigation) or A/C display (without navigation) receives rear window defogger switch signals, rear window defogger indicator is displayed 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.

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 terminals 5 and 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 (LH and RH) terminal 2.

Door mirror (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.