Pinpoint Test J: The Defrost System is Inoperative
Glass, Frames and Mechanisms
Pinpoint Test J: The Defrost System is Inoperative
Refer to Wiring Diagram Set 56, Heated Window for schematic and connector information Electrical Diagrams.
Normal Operation
The engine must be running for the rear window defrost system to operate. When the rear window defrost switch (integral to the HVAC module) is pressed, a ground signal is sent to the Body Control Module (BCM). When the BCM (Body Control Module) receives the defrost request signal, it supplies voltage to the rear window defrost grid. When the rear window defrost is active, the BCM (Body Control Module) supplies voltage through a dedicated feedback circuit to the HVAC module to illuminate the LED indicator.
- DTC B1013:23 (Heater Rear Defog Switch: Signal Stuck Low)- sets if the rear window defrost switch is active during self-test, or if the rear window defrost switch has been active for more than 2 minutes.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Rear window defrost grid
- HVAC module
- BCM (Body Control 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.
J1 CHECK THE BCM (Body Control Module) REAR DEFROST SWITCH (R_DEFRST_SW) PID OPERATION
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger- BCM (Body Control Module).
- While monitoring the BCM (Body Control Module) R_DEFRST_SW PID, press and release the rear window defrost switch.
Does the PID agree with the rear window defrost switch status?
Yes
GO to J5.
No
If DTC B1013:23 is present, GO to J3.
If DTC B1013:23 is not present, GO to J2.
J2 CHECK THE HVAC MODULE (REAR WINDOW DEFROST SWITCH) GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Measure the resistance between HVAC module C228A-13, circuit GD115 (BK/GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to J3.
No
REPAIR the circuit. TEST the system for normal operation.
J3 CHECK THE BCM (Body Control Module) REAR DEFROST SWITCH (R_DEFRST_SW) PID OPERATION
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Connect a fused jumper wire between HVAC module C228A-13, circuit GD115 (BK/GY), harness side and HVAC module C228A-16, circuit CRD09 (BU/GY), harness side.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger- BCM (Body Control Module).
- Observe the BCM (Body Control Module) R_DEFRST_SW PID status.
- Remove the fused jumper wire.
- Observe the BCM (Body Control Module) R_DEFRST_SW PID status.
Did the PID state change when the fused jumper wire was removed?
Yes
INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to J4.
J4 CHECK THE REAR WINDOW DEFROST SWITCH CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280E.
- Measure the resistance between BCM (Body Control Module) C2280E-10, circuit CRD09 (BU/GY), harness side and HVAC module C228A-16, circuit CRD09 (BU/GY), harness side; and between BCM (Body Control Module) C2280E-10, circuit CRD09 (BU/GY), harness side and ground.
Is the resistance less than 5 ohms between the BCM (Body Control Module) and the HVAC module; and greater than 10,000 ohms between the BCM (Body Control Module) and ground?
Yes
GO to J9.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
J5 CHECK FOR VOLTAGE TO THE REAR WINDOW DEFROST GRID
- Ignition OFF.
- Disconnect: Rear Window Defrost Grid C402A.
- Start the engine.
- Activate the rear window defrost switch.
- 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
If the rear window defrost switch LED is illuminated, GO to J8.
If the rear window defrost switch LED is not illuminated, GO to Pinpoint Test L to diagnose the LED circuit Pinpoint Test L: The Defrost System LED Does Not Illuminate When the Defrost System is Active.
No
GO to J6.
J6 CHECK THE BCM (Body Control Module) VOLTAGE FEED FOR AN OPEN
- Ignition OFF.
- Measure the voltage between BCM (Body Control Module) C2280A-1, circuit SBB34 (BN/RD), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to J7.
No
VERIFY BJB (Battery Junction Box) fuse 34 (30A) is OK, If OK, REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
J7 CHECK THE REAR WINDOW DEFROST GRID VOLTAGE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280C.
- Measure the resistance between BCM (Body Control Module) C2280C-10, circuit CRD06 (BN/YE), harness side and rear window defrost grid C402A-1, circuit CRD06 (BN/YE), harness side; and between BCM (Body Control Module) C2280C-10, circuit CRD06 (BN/YE), harness side and ground.
Is the resistance less than 5 ohms between the BCM (Body Control Module) and the rear window defrost grid; and greater than 10,000 ohms between the BCM (Body Control Module) and ground?
Yes
GO to J9.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
J8 CHECK THE REAR WINDOW DEFROST GRID GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Rear Window Defrost C402B.
- Measure the resistance between rear window defrost grid C402B-1, circuit GD143 (BK/VT), harness side and ground.
Is the resistance less than 5 ohms?
Yes
CARRY OUT the Grid Wire component test Component Tests and General Diagnostics. REPAIR the rear window defrost grid or INSTALL a new rear window glass as necessary. REFER to Window Grid Wire Repair Window Grid Wire Repair or Window Glass - Rear Window Glass - Rear. TEST the system for normal operation.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
J9 CHECK FOR CORRECT BCM (Body Control Module) MODULE OPERATION
- Disconnect all the BCM (Body Control Module) connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all the BCM (Body Control 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 BCM (Body Control 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. CLEAR all DTCs. TEST the system for normal operation.