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

Glass, Frames and Mechanisms

Pinpoint Tests

Pinpoint Test F: 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 rear window defrost switch pressed, the rear window defrost switch supplies a ground input to the Generic Electronic Module (GEM). The GEM then activates the rear window defrost relay by grounding the rear window defrost relay coil. When the rear window defrost relay is activated, voltage is supplied to the LH and RH door.

- DTC B1350 (Heated Backlite Relay Short to Ground) - sets when an open or short to ground is detected in the rear window defrost relay coil control circuit.

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


PINPOINT TEST F: 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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F1 CHECK FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: Rear Window Defrost Relay.
- Start the engine.
- With the engine running, check the defrost switch indicator status.
- Is the defrost switch indicator illuminated?

Yes
REPAIR circuit 15S-HB3 (GN/BU) for a short to voltage. TEST the system for normal operation.

No
GO to F2.

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F2 CHECK THE GEM OPERATION


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 86, circuit 15S-HB20 (GN/BK) and rear window defrost relay socket pin 85, circuit 15-DA1G (GN/YE).




- Does the test light illuminate?

Yes
GO to F3.

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

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F3 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: GEM C201B.
- Measure the resistance between rear window defrost relay socket pin 86, circuit 15S-HB20 (GN/BK), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to F4.

No
REPAIR the circuit. TEST the system for normal operation.

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F4 CHECK FOR CORRECT GEM MODULE OPERATION


- Disconnect the GEM electrical connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect the GEM 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 GEM. REFER to Multifunction Electronic Modules Service and Repair. 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.

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