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

Glass, Frames and Mechanisms

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

Refer to Wiring Diagrams Set 56, Heated Window for schematic and connector information. Electrical Diagrams

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 (Generic Electronic Module) 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 (Generic Electronic Module)

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.

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.

F2 CHECK THE GEM (Generic Electronic Module) 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 at the beginning. 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 15S-HB20 (GN/BK) and rear window defrost relay socket pin 1, 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.

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

- Ignition OFF.

- Disconnect: GEM (Generic Electronic Module) C201B.

- Measure the resistance between rear window defrost relay socket pin 2, 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.

F4 CHECK FOR CORRECT GEM (Generic Electronic Module) MODULE OPERATION

- Disconnect the GEM (Generic Electronic Module) electrical connectors.

- Check for:
- corrosion.

- pushed-out pins.


- Connect the GEM (Generic Electronic 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 GEM (Generic Electronic Module). 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.