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

WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: 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.

J1 CHECK CIRCUIT CRD06 (BN/YE) FOR A SHORT TO VOLTAGE

Disconnect: Rear Window Defrost Relay.

Disconnect: Rear Window Defrost Grid Power C402A.

Start the engine.

Activate the rear defrost switch and measure the voltage between rear window defrost grid power C402A-1 , circuit CRD06 (BN/YE) and ground.

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Is any voltage present?

Yes	REPAIR the circuit. TEST the system for normal operation.
No	GO to J2.

J2 CHECK THE HVAC MODULE OUTPUT

NOTE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning of this article. 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.

Ignition OFF.

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).

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Start the engine.

Does the test light illuminate?

Yes	GO to J3.
No	INSTALL a new rear window defrost relay. TEST the system for normal operation.

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

Ignition OFF.

Disconnect: HVAC Module - EATC C228A or HVAC Module - EMTC C2357B.

Measure the resistance between rear window defrost relay socket pin 2, circuit CH122 (WH/OG), harness side and ground.

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Is the resistance greater than 10, 000 ohms?

Yes	GO to J4.
No	REPAIR the circuit. TEST the system for normal operation.

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. Climate Control . 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.