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, Heated Window for schematic and connector information. Diagrams By Number

Normal Operation

When the engine is running and the defrost switch is pressed, the HVAC activates the rear window defrost relay by providing ground to the relay coil through circuit CH122 (WH/OG). When the defrost relay is activated, power is supplied from the rear window defrost relay through circuit CRD06 (BN/YE) to the rear window defrost grid. Ground is supplied to the rear window defrost grid through circuit GD147 (BK/VT).

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



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

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G1 CHECK CIRCUIT CRD06 (BN/YE) FOR A SHORT TO VOLTAGE


- Disconnect: Rear Window Defrost Relay.
- Ignition ON.
- Is the rear window defrost ON?

Yes
REPAIR circuit CRD06 (BN/YE) for a short to voltage. TEST the system for normal operation.

No
GO to G2.

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G2 CHECK THE REAR WINDOW DEFROST RELAY


- Start the engine.
- Measure the resistance between rear window defrost relay socket pin 86, circuit CH122 (WH/OG), harness side and ground.




- Is the resistance less than 60 ohms?

Yes
GO to G3.

No
INSTALL a new rear window defrost relay. 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 Automatic Temperature Control (EATC) C228b or HVAC Module - Electronic Manual Temperature Control (EMTC) C2357a.
- Measure the resistance between rear window defrost relay socket pin 86, circuit CH122 (WH/OG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to G4.

No
REPAIR short to ground in circuit CH122 (WH/OG). TEST the system for normal operation.

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G4 CHECK FOR CORRECT HVAC MODULE OPERATION


- Disconnect all HVAC module connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all 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. Concern may have been caused by a loose or corroded connector. TEST the system for normal operation.

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