Test N
PINPOINT TEST N: THE DEFROST SYSTEM WILL NOT SHUT OFF AUTOMATICALLYTest N1-N2:
Test N3:
Normal Operation
Under normal operation the heated backlight relay receives power from circuit 185 (BK) and central junction box fuse 10 (10A). When the rear window defrost switch is depressed on the temperature control module a message is sent to the instrument cluster module (ICM) through the multiplex link system. Once the ICM receives the message to turn on the rear window defrost the ICM grounds circuit 1009 (OG/YE) to activate the heated backlight relay. Power is then sent to the rear window defrost grid through circuit 186 (BN/LB) from the heated backlight relay. The rear window defrost grid then receives ground through circuit 1205 (BK) to chassis ground.
Possible Causes
- Inoperative ICM.
- Inoperative heated backlight relay.
- Multiplex communication error.
- Short to voltage in circuit 186 (BN/LB).
- Short to ground in circuit 1009 (OG/YE).