Test G: the Defrost System Does Not Shut Off Automatically - On At All Times
PINPOINT TEST G: THE DEFROST SYSTEM DOES NOT SHUT OFF AUTOMATICALLY - ON AT ALL TIMESG1-G4:
G5-G6:
Normal Operation
Under normal operation, the rear defrost relay receives power from the battery junction box (BJB) through circuit SBB15 (WH/RD).
For vehicles equipped with dual auto temp control (DATC) modules, when the rear window defrost switch is depressed, a message is sent to the smart junction box (SJB) through the controller area network (CAN). When the SJB receives a rear window defrost ON message through the CAN, the SJB starts an internal 10 minute timer and grounds the rear defrost relay coil, which activates the rear defrost relay. When the rear defrost relay is active, power is sent to the rear window defrost grid through circuit CRD06 (BN/YE) from the rear defrost relay. The rear window defrost grid is grounded to the chassis through circuit GD150 (BK/WH).
For vehicles equipped with manual climate control assemblies, when the rear window defrost switch is depressed, a ground signal is sent to the SJB through circuit CRD09 (BU/GY). When the SJB receives ground through circuit CRD09 (BU/GY), the SJB starts an internal 10 minute timer and grounds the rear defrost relay coil, which activates the rear defrost relay. When the rear defrost relay is active, power is sent to the rear window defrost grid through circuit CRD06 (BN/YE) from the rear defrost relay. The rear window defrost grid is grounded to the chassis through circuit GD150 (BK/WH).
Possible Causes
- Inoperative SJB
- Inoperative manual climate control assembly or DATC module
- Inoperative rear defrost relay
- Short to voltage in circuit CRD06 (BN/YE)
- For vehicles equipped with manual climate control, a short to ground in circuit CRD09 (BU/GY)