Pinpoint Test F: DTC B1349 - Heated Backlite Relay Short to Battery

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Heated Windows for schematic and connector information.

Normal Operation 

The key must be in the START or RUN position for the heated rear window to operate. When the rear window defrost switch is pressed, a momentary ground is supplied to the driver's door module (DDM) through circuit 1010 (DB/OG). The DDM provides a ground for the rear window defrost relay coil on circuit 688 (GY/LB). When the rear window defrost relay coil is energized, the relay switch closes, providing voltage to the heated rear window grid, the heated rear window indicator, and the heated exterior mirror (if equipped) through circuit 186 (BN/LB). The heated rear window grid and the rear window defrost switch are grounded through circuit 57 (BK).

This pinpoint test is intended to diagnose the following:

• Wiring, terminals or connectors
• Rear window defrost relay
• DDM

PINPOINT TEST F: DTC B1349 - HEATED BACKLIGHT RELAY SHORT TO BATTERY 

1. F1 CHECK CIRCUIT 688 (GY/LB) FOR SHORT TO VOLTAGE 
   • Disconnect: DDM C501b
   • Disconnect: Rear Window Defrost Relay
   • Key in ON position.
   Fig 1: Checking Circuit For Short To Voltage
   Courtesy of FORD MOTOR CO.
   • Measure the voltage between DDM C501b-15, circuit 688 (GY/LB), harness side and ground.
   • Is there any voltage indicated? 
   1. YES  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
   2. NO  : Go to  F2.
2. F2 CHECK THE REAR WINDOW DEFROST RELAY FOR CORRECT OPERATION 
   • Carry out the ISO relay test for the rear window defrost relay. Refer to COMPONENT TESTING article.
   • Is the rear window defrost relay OK? 
   1. YES  : Go to  F3.
   2. NO  : INSTALL a new rear window defrost relay. CLEAR the DTCs. REPEAT the self-test.
3. F3 CHECK FOR CORRECT DDM OPERATION 
   • Disconnect all the DDM connectors.
   • Check for:
     • corrosion.
     • pushed-out pins.
   • Connect all the DDM connectors and make sure they seat correctly.
   • Operate the system and verify the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new DDM. REFER to MULTIFUNCTION ELECTRONIC MODULES article. TEST the system for normal operation.
   2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.