Pinpoint Test J: The Defrost System Is Inoperative
Glass, Frames and Mechanisms
Pinpoint Tests
Pinpoint Test J: The Defrost System is Inoperative
Refer to Wiring Diagram Set 56, Heated Window for schematic and connector information. Diagrams By Number
Normal Operation
The rear window defrost relay, located in the Battery Junction Box (BJB), receives power from circuit CBP45 (YE). When the rear window defrost switch (integral to the HVAC module) is pressed, the HVAC module grounds circuit CH122 (WH/OG) to activate the rear window defrost relay. When the rear window defrost relay is activated, power is sent from the rear window defrost relay to the rear window defrost grid through circuit CRD06 (BN/YE). The rear window defrost grid is grounded through circuit GD149 (BK/GY).
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Rear window defrost relay
- HVAC module
PINPOINT TEST J: THE DEFROST SYSTEM IS INOPERATIVE
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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J1 CHECK CIRCUIT CRD06 (BN/YE) FOR POWER
- Disconnect: Rear Window Defrost Grid C402A.
- Start the engine.
- Turn the rear window defrost switch on.
- Measure the voltage between rear window defrost grid C402A-1, circuit CRD06 (BN/YE), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to J4.
No
VERIFY BJB fuse 39 (40A) is OK. If OK, GO to J2.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. REPAIR the circuit. TEST the system for normal operation.
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J2 CHECK CIRCUIT CRD06 (BN/YE) FOR AN OPEN
- Ignition OFF.
- Disconnect: Rear Window Defrost Relay.
- Measure the resistance between rear window defrost grid C402A-1, CRD06 (BN/YE), harness side and rear window defrost relay pin 87, CRD06 (BN/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J3.
No
REPAIR the circuit. TEST the system for normal operation.
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J3 CHECK THE VOLTAGE SUPPLY TO THE REAR WINDOW DEFROST RELAY
- Ignition ON.
- Measure the voltage between rear window defrost relay pin 30, circuit SDC02 (RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to J5.
No
VERIFY BJB fuse 1 (40A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. REPAIR the circuit. TEST the system for normal operation.
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J4 CHECK CIRCUIT GD149 (BK/GY) FOR AN OPEN
- Ignition OFF.
- Disconnect: Rear Window Defrost Grid C402B.
- Measure the resistance between rear window defrost grid C402B-1, circuit GD149 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the Grid Wire Test Component Tests and General Diagnostics. REPAIR the rear window defrost grid or INSTALL a new liftgate glass. REFER to Window Grid Wire Repair Window Grid Wire Repair. TEST the system for normal operation.
No
GO to J6.
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J5 CHECK CIRCUIT CBP45 (YE) FOR VOLTAGE
- Measure the voltage between rear window defrost relay pin 85, circuit CBP45 (YE), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to J6.
No
VERIFY SJB fuse 45 (5A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. REPAIR the circuit. TEST the system for normal operation.
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J6 CHECK THE HVAC MODULE OUTPUT
- Start the engine.
- Turn the rear window defrost switch on.
- Measure the resistance between rear window defrost relay pin 86, circuit CH122 (WH/OG) and ground.
- Is the resistance less than 60 ohms?
Yes
GO to J7.
No
GO to J8.
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J7 CHECK THE REAR WINDOW DEFROST RELAY
- Ignition OFF.
- Carry out the rear window defrost relay component test.
- Did the rear window defrost relay pass the component test?
Yes
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
No
INSTALL a new rear window defrost relay. TEST the system for normal operation.
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J8 CHECK CIRCUIT CH122 (WH/OG) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - Electronic Automatic Temperature Control (EATC) C228B or HVAC module - Electronic Manual Temperature Control (EMTC) C2357A.
- Measure the resistance between rear window defrost relay socket, circuit CH122 (WH/OG), harness side and HVAC module - EATC C228B-23, circuit CH122 (WH/OG), harness side; or HVAC module - EMTC C2357A-3, circuit CH122 (WH/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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