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

Glass, Frames and Mechanisms

Pinpoint Tests

Pinpoint Test J: 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

With the engine running, the HVAC module activates the rear window defrost relay by providing grounding 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 GD150 (BK/WH).

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

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

NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

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J1 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 J2.

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J2 CHECK THE HVAC MODULE OUTPUT


NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.

- Start the engine.
- Connect a 12-volt incandescent test light between rear window defrost relay socket pin 2, circuit CH122 (WH/OG) and rear window defrost relay socket pin 1, circuit CBB52 (GN/WH).




- Does the test light illuminate?

Yes
GO to J3.

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

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J3 CHECK CIRCUIT CH122 (WH/OG) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: HVAC Module - EATC C228B or HVAC Module - EMTC C2357B.
- Measure the resistance between rear window defrost relay socket pin 2, circuit CH122 (WH/OG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
REPAIR short to ground in circuit CH122 (WH/OG). TEST the system for normal operation.

No
GO to J4.

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J4 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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