Pinpoint Test 7: The Defrost System Will Not Shut Off Automatically

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PINPOINT TEST 7: THE DEFROST SYSTEM WILL NOT SHUT OFF AUTOMATICALLY - HYBRID

Normal Operation

The rear window defrost relay receives power from the battery junction box (BJB) fuse 35 (10A) on circuit (Y/GY). When the rear window defrost switch is pressed to the ON position, the dual automatic temperature control (DATC) module activates the rear window defrost relay, which then supplies 12 volts to the rear window defrost grid on circuit (BR/Y). The rear window defrost grid is grounded through circuit (B/GY).

- DTC B12BF - Heated backlight/mirror relay drive circuit open or shorted to ground, heated backlight and heated mirrors wire failure, relay drive circuit open or shorted to ground.

Possible Causes
- Rear window defrost relay
- Rear window defrost switch
- DATC module

Diagnostic Procedure

Step 1-Step 3:

Step 9: