Pinpoint Test H: The Defrost System Is Inoperative - ON Indicator

Glass, Frames and Mechanisms

Pinpoint Tests

Pinpoint Test H: The Defrost System is Inoperative - ON Indicator

Refer to Wiring Diagram Set 56, Heated Windows for schematic and connector information. Diagrams By Number

Normal Operation

When the rear window defrost relay is energized, switched voltage is supplied to the rear window defrost switch indicator through circuit 59 (DG/VT). The switch is grounded through circuit 57 (BK).

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

PINPOINT TEST H: THE DEFROST SYSTEM IS INOPERATIVE - ON INDICATOR

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H1 CHECK THE HEATED REAR WINDOW OPERATION


- Start the engine.
- Press the rear window defrost switch to ON.
- Does the rear window defrost grid operate?

Yes
GO to H2.

No
GO to Pinpoint Test E. Pinpoint Test E: The Defrost System Is Inoperative

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H2 CHECK THE VOLTAGE TO THE REAR WINDOW DEFROST SWITCH INDICATOR


- Ignition OFF.
- Disconnect: Rear Window Defrost Switch C241.
- Start the engine.
- Enter the following diagnostic mode on the scan tool: DDM DataLogger.
- Trigger the DDM PID HEAT_BCK ON.
- Measure the voltage between rear window defrost switch C241-4, circuit 59 (DG/VT), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to H3.

No
VERIFY the BJB fuse 24 (10A) is OK. If OK, GO to H4. If not OK, REFER to Wiring Diagrams to identify the possible causes of the circuit short. REPAIR the circuit. TEST the system for normal operation. Diagrams By Number

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H3 CHECK CIRCUIT 57 (BK) FOR AN OPEN


- Ignition OFF.
- Measure the resistance between rear window defrost switch C241-7, circuit 57 (BK), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
INSTALL a new rear window defrost switch. TEST the system for normal operation.

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

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H4 CHECK CIRCUIT 186 (BN/LB) FOR AN OPEN


- Disconnect: BJB Fuse 24 (10A).
- Measure the voltage between input cavity of BJB fuse 24 (10A), circuit 186 (BN/LB) and ground.




- Is the voltage greater than 10 volts?

Yes
REPAIR circuit 59 (DG/VT). TEST the system for normal operation.

No
REPAIR circuit 186 (BN/LB). TEST the system for normal operation.

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