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) - Sets when an open or short to ground is detected in the relay control circuit.
- DTC B1C83:14 (Rear Defog Relay: Circuit Short to Ground or Open) - Sets when an open or short to ground is detected on the relay control circuit.
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
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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G1 CHECK CIRCUIT CRD06 (BN/YE) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Rear Window Defrost Relay.
- Disconnect: Rear Window Defrost Grid C402A.
- Ignition ON.
- Is any voltage present?
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 HVAC MODULE
NOTICE: 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 system. 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 CBB35 (YE/GY).
- Does the test light illuminate?
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 Manual Temperature Control (EMTC) C2357A or HVAC Module - Dual Automatic Temperature Control (DATC) C2356A.
- Measure the resistance between rear window defrost relay socket pin 2, circuit CH122 (WH/OG) and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to G4.
No
REPAIR the short to ground in circuit CH122 (WH/OG). 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. REFER to Body Control Systems. 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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