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

Glass, Frames and Mechanisms

Pinpoint Tests

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

Refer to Wiring Diagram Set 56 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Heated Window for schematic and connector information. Diagrams By Number

Normal Operation

The rear window defrost relay receives power from the Battery Junction Box (BJB) fuse 35 (10A) on circuit CBB35 (YE/GY). When the rear window defrost switch is pressed to the ON position, the HVAC module activates the rear window defrost relay by grounding circuit CH122 (WH/OG). When activated, the rear window defrost relay supplies 12 volts to the rear window defrost grid on circuit CRD06 (BN/YE). The rear window defrost grid is grounded through circuit GD149 (BK/GY) to ground.

The HVAC module will deactivate the rear window defrost relay when one of the following conditions is met:

- The rear window defrost switch is pressed when the feature is active.
- The ignition switch state is changed from ON to OFF/LOCK.
- The 15-minute timing function is complete.

- 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.

This pinpoint test is intended to diagnose the following:
- Rear window defrost relay
- Wiring, terminals or connectors
- Rear window defrost switch (integral to HVAC module)
- HVAC module



PINPOINT TEST G: THE DEFROST SYSTEM WILL NOT SHUT OFF AUTOMATICALLY

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G1 CHECK THE REAR WINDOW DEFROST GRID WITH THE RELAY REMOVED


- Ignition OFF.
- Disconnect: Rear Window Defrost Relay.
- Ignition ON.
- Check the rear window defrost grid with the relay removed.
- Is the rear window defrost still ON?

Yes
REPAIR the short to voltage in circuit CRD06 (BN/YE). CLEAR all DTCs. TEST the system for normal operation.

No
GO to G2.

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G2 CHECK THE REAR WINDOW DEFROST RELAY


- Carry out the Rear Window Defrost Relay component test.

- Did the rear window defrost relay pass the component test?

Yes
GO to G3.

No
INSTALL a new rear window defrost relay. CLEAR the DTCs. TEST the system for normal operation.

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G3 CHECK CIRCUIT CH122 (WH/OG) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: HVAC Module - Electronic Manual Temperature Control (EMTC) C2357a or HVAC Module - Electronic Automatic Temperature Control (EATC) C2356a.
- Measure the resistance between rear window defrost relay pin 2, circuit CH122 (WH/OG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to G4.

No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.

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G4 CHECK FOR CORRECT HVAC MODULE OPERATION


- Disconnect all the HVAC module connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all the HVAC module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new HVAC module. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR all DTCs. TEST the system for normal operation.

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