Pinpoint Test E: The Defrost System Is Inoperative
Glass, Frames and Mechanisms
Pinpoint Tests
Pinpoint Test E: The Defrost System is Inoperative
Refer to Wiring Diagram Set 56, Heated Windows for schematic and connector information. Diagrams By Number
Normal Operation
The rear window defrost system is controlled by the Driver Door Module (DDM). The ignition switch must be in RUN for the DDM to operate. When the rear window defrost switch is pressed, the DDM provides a ground for the rear window defrost relay coil through circuit 688 (GY/LB). The rear window defrost relay coil is energized, providing battery voltage to the antenna module on circuit 186 (BN/LB). The antenna module then supplies voltage and ground to the rear window defrost grid.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Rear window defrost relay
- Rear window defrost switch
- Rear window defrost grid
- Antenna module
- DDM
PINPOINT TEST E: THE DEFROST SYSTEM IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
-------------------------------------------------
E1 CHECK THE REAR WINDOW DEFROST SWITCH CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: DDM C501a.
- While pressing the rear window defrost switch, measure resistance between DDM C501a-23, circuit 1010 (DB/OG), harness side and ground.
- Is the resistance less than 5 ohms with the rear window defrost switch pressed?
Yes
CONNECT the DDM C501a. GO to E4 .
No
GO to E2.
-------------------------------------------------
E2 CHECK CIRCUIT 1010 (DB/OG) FOR AN OPEN
- Disconnect: Rear Window Defrost Switch C241.
- Measure the resistance between DDM C501a-23, circuit 1010 (DB/OG), harness side, and rear window defrost switch C241-1, circuit 1010 (DB/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E3.
No
REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
E3 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Measure the resistance between rear window defrost switch C241-2, 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.
-------------------------------------------------
E4 CHECK THE SIGNAL INPUT
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.
- Start the engine.
- Press the rear window defrost switch to ON.
- 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 E6.
No
GO to E5.
-------------------------------------------------
E5 CHECK CIRCUIT 688 (GY/LB) FOR AN OPEN
- Ignition OFF.
- Disconnect: DDM 501b.
- Measure the resistance between rear window defrost relay pin 85, circuit 688 (GY/LB), harness side and the DDM C501b-15, circuit 688 (GY/LB), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E12.
No
REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
E6 CHECK CIRCUIT 185 (BK) FOR VOLTAGE
- Measure the voltage between rear window defrost relay pin 30, circuit 185 (BK), harness side and ground; and between rear window defrost relay pin 86, circuit 185 (BK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to E7.
No
VERIFY the Battery Junction Box (BJB) fuse 107 (40A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation. 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
-------------------------------------------------
E7 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 E8.
No
INSTALL a new rear window defrost relay. TEST the system for normal operation.
-------------------------------------------------
E8 CHECK THE RELAY OUTPUT TO THE HEATED REAR WINDOW GRID
- Ignition OFF.
- Connect: Rear Window Defrost Relay.
- Disconnect: Rear Window Defrost Grid Connector.
- Start the engine.
- Press the rear window defrost switch to on.
- Measure the voltage between rear window defrost grid connector, harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to E11.
No
GO to E9.
-------------------------------------------------
E9 CHECK THE RELAY OUTPUT TO THE ANTENNA MODULE
- Ignition OFF.
- Disconnect: Antenna Module C402A.
- Start the engine.
- Press the rear window defrost switch to on.
- Measure the voltage between antenna module C402A-1, circuit 186 (BN/LB), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new antenna module. REFER to Information and Entertainment Systems Service and Repair. TEST the system for normal operation.
No
GO to E10.
-------------------------------------------------
E10 CHECK CIRCUIT 186 (BN/LB) FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: BJB Fuse 24 (10A).
- Disconnect: Rear Window Defrost Relay.
- Measure the resistance between antenna module C402A-1, circuit 186 (BN/LB), harness side and pin 87, circuit 186 (BN/LB), harness side; and between antenna module C402A-1, circuit 186 (BN/LB), harness side and ground.
- Is the resistance less than 5 ohms between the antenna module and the rear window defrost relay; and greater than 10,000 ohms between the antenna module and ground?
Yes
INSTALL a new rear window defrost relay. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
E11 CHECK THE GROUND FOR THE HEATED REAR WINDOW GRID
- Ignition OFF.
- Disconnect: Rear Window Defrost Grid Ground Connector.
- Measure the resistance between rear window defrost grid ground connector, circuit 57 (BK), 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. REFER to Window Grid Wire Repair Window Grid Wire Repair. TEST the system for normal operation.
No
INSTALL a new antenna module. REFER to Information and Entertainment Systems Service and Repair. TEST the system for normal operation.
-------------------------------------------------
E12 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.
-------------------------------------------------