Heated Glass Element: Description and Operation

System Description
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 20 A fuse [No. 75 and 80, located in the IPDM E/R]
- to rear window defogger relay terminal 3 and 6.
- through 40 A fusible link (letter F, located in the fuse and fusible link box)
- to BCM terminal 55.
- through 10 A fuse [No. 18, located in the fuse block (J/B)]
- to BCM terminal 42.
- through 10 A fuse [No. 19, located in the fuse block (J/B)]
- to unified meter and A/C amp. terminal 21.

With the ignition switch turned to ON or START position, power is supplied
- through 10 A fuse [No. 1, located in the fuse block (J/B)]
- to BCM terminal 38.
- through 10 A fuse [No. 12, located in the fuse block (J/B)]
- to unified meter and A/C amp. terminal 22 and rear window defogger relay terminal 1
- and then through unified meter and A/C amp.
- to A/C controller (rear window defogger switch) terminal 72 and 84.

Ground is supplied
- to BCM terminal 52
- through body grounds M30, and M66.
- to unified meter and A/C amp. terminal 29 and 30
- through body grounds M30 and M66.
- to internal CPU of IPDM E/R terminal 38 and 60
- through body grounds E17, E43 and F152.

When A/C controller (rear window defogger switch) is turned ON, Rear window defogger switch signals are transmitted,
- through A/C controller terminal 87
- to unified meter and A/C amp.

Then ground is supplied
- to BCM terminal 9
- through unified meter and A/C amp. terminal 38
- through unified meter and A/C amp. terminal 30
- through body grounds M30 and M66.

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

Then it sends rear window defogger switch signals to IPDM E/R via DATA LINE (CAN H, CAN L).

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 internal CPU of IPDM E/R
- through IPDM E/R terminal 60
- through body grounds E17, E43 and F152, and then rear window defogger relay is energized.

When rear window defogger relay is turned ON, Signals are transmitted
- to rear window defogger terminal 1
- through rear window defogger relay terminals 5 and 7 (For Coupe)
- through rear window defogger relay terminal 5. (For Roadster)

Rear window defogger terminal 2 is grounded through body ground D212. (For Coupe)

Rear window defogger terminal 2 is grounded through body ground B5, B6 and T14. (For Roadster)

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

When rear window defogger relay is turned ON, Power is supplied
- through rear window defogger relay terminals 5 and 7 (For Coupe)
- through rear window defogger relay terminal 7 (For Roadster)
- through fuse block (J/B) terminal 2C
- through 10 A 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 2.

Door mirror defogger (Driver side and passenger side) terminal 1 is grounded through body grounds M30 and M66.

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

When rear window defogger relay is turned ON, Power is supplied
- through rear window defogger relay terminals 5 and 7 (For Coupe)
- through rear window defogger relay terminal 5. (For Roadster)
- to unified meter and A/C amp. terminal 56

Then ground is supplied
- to A/C controller terminal 78
- through unified meter and A/C amp.
- through unified meter and A/C amp. terminal 29 and 30
- through body grounds M30 and M66.

This energizes rear window defogger indicator.

CAN Communication System Description
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

CAN Communication Unit
Refer to Information Bus.