Pinpoint Test G: The Defrost System Does Not Shut Off Automatically
Glass, Frames and Mechanisms
Pinpoint Tests
Pinpoint Test G: The Defrost System Does Not Shut Off Automatically
Refer to Wiring Diagram Set 56, Heated Windows for schematic and connector information. Diagrams By Number
Normal Operation
The key must be in the START or RUN position for the rear window defrost system to operate. When the rear window defrost switch is pressed, a momentary ground is supplied to the Driver Door Module (DDM) through circuit 1010 (DB/OG). The DDM provides a ground for the rear window defrost relay coil on circuit 688 (GY/LB). When the rear window defrost relay coil is energized, the relay switch closes, providing voltage to the rear window defrost grid, the rear window defrost indicator, and the heated exterior mirror (if equipped) through circuit 186 (BN/LB). The rear window defrost grid and the rear window defrost switch are grounded through circuit 57 (BK).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Rear window defrost switch
- Rear window defrost relay
- DDM
PINPOINT TEST G: THE DEFROST SYSTEM DOES NOT SHUT OFF AUTOMATICALLY
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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G1 CHECK THE REAR WINDOW DEFROST SWITCH CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: DDM C501a.
- Measure the resistance between DDM C501a-23, circuit 1010 (DB/OG), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to G3.
No
GO to G2.
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G2 CHECK HEATED CIRCUIT 1010 (DB/OG) FOR A SHORT TO GROUND
- Disconnect: Rear Window Defrost Switch C241.
- Measure the resistance between DDM C501a-23, circuit 1010 (DB/OG), harness side and ground.
- Is the resistance greater than 10,000 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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G3 CHECK CIRCUIT 688 (GY/LB) FOR A SHORT TO GROUND
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use the test lamp probe.
- Disconnect: Rear Window Defrost Relay.
- Connect a 12-volt incandescent test lamp between rear window defrost relay socket pin 85, circuit 688 (GY/LB) and rear window defrost relay socket pin 86, circuit 185 (BK).
- Does the test lamp illuminate?
Yes
GO to G5.
No
GO to G4.
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G4 CHECK THE DDM FOR A SHORT TO GROUND
- Disconnect: DDM C501b.
- Measure the resistance between rear window defrost relay pin 85, circuit 688 (GY/LB), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to G7.
No
REPAIR the circuit. TEST the system for normal operation.
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G5 CHECK CIRCUIT 186 (BN/LB) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between rear window defrost relay pin 87, circuit 186 (BN/LB), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
GO to G6.
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G6 CHECK THE REAR WINDOW DEFROST RELAY FOR CORRECT OPERATION
- Carry out the ISO relay component test for the rear window defrost relay.
Refer to Rear Window Defrost Relay for component testing.
- Is the rear window defrost relay OK?
Yes
GO to G7.
No
INSTALL a new rear window defrost relay. TEST the system for normal operation.
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G7 CHECK FOR CORRECT DDM OPERATION
- Disconnect all the DDM connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all the DDM 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 DDM. 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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