Pinpoint Test F: The Defrost System Is Inoperative
Glass, Frames and Mechanisms
Pinpoint Tests
Pinpoint Test F: The Defrost System is Inoperative
Refer to Wiring Diagram Set 56 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Heated Window for schematic and connector information. Diagrams By Number
Normal Operation
The rear window defrost relay receives power from the Battery Junction Box (BJB) fuse 35 (10A) on circuit CBB35 (YE/GY). When the rear window defrost switch is pressed to the ON position, the HVAC module activates the rear window defrost relay by grounding circuit CH122 (WH/OG). When activated, the rear window defrost relay supplies 12 volts to the rear window defrost grid on circuit CRD06 (BN/YE). The rear window defrost grid is grounded through circuit GD149 (BK/GY).
The HVAC module will deactivate the rear window defrost relay when one of the following conditions is met:
- The rear window defrost switch is pressed when the feature is active.
- The ignition switch state is changed from ON to OFF/LOCK.
- The 15-minute timing function is complete.
- DTC B12BE - Heated backlight/mirror relay drive circuit shorted to battery voltage, heated backlight and heated mirrors wire failure, relay drive circuit shorted to battery.
- DTC B12BF - Heated backlight/mirror relay drive circuit open or shorted to ground, heated backlight and heated mirrors wire failure, relay drive circuit open or shorted to ground.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Rear window defrost relay
- Rear window defrost switch (integral to the HVAC module)
- Rear window defrost grid
- HVAC module
PINPOINT TEST F: THE DEFROST SYSTEM IS INOPERATIVE
-------------------------------------------------
F1 CHECK THE REAR WINDOW DEFROST RELAY
- Ignition OFF.
- Disconnect: Rear Window Defrost Relay .
- Carry out the Rear Window Defrost Relay component test.
- Did the rear window defrost relay pass the component test?
Yes
GO to F2.
No
INSTALL a new rear window defrost relay. CLEAR all DTCs. TEST the system for normal operation.
-------------------------------------------------
F2 CHECK THE REAR WINDOW DEFROST RELAY FEED CIRCUITS FOR VOLTAGE
- Ignition ON.
- Measure the voltage between rear window defrost relay pin 3, CBB35 (YE/GY), harness side and ground; and between rear window defrost relay pin 1, circuit CBB35 (YE/GY), harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to F3.
No
VERIFY BJB fuse 35 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to Wiring Diagrams to identify the possible causes of the circuit short. CLEAR all DTCs.
TEST the system for normal operation.
-------------------------------------------------
F3 CHECK CIRCUIT CRD06 (BN/YE) FOR VOLTAGE
- Connect: Rear Window Defrost Relay.
- Disconnect: Rear Window Defrost Grid C402a.
- Ignition ON.
- Press the rear window defrost switch to the ON position.
- 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 F4.
No
VERIFY BJB fuse 2 (30A) is OK. If OK, GO to F5. If not OK, REFER to Wiring Diagrams to identify the possible causes of the circuit short.
-------------------------------------------------
F4 CHECK THE GRID GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Rear Window Defrost 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 Component Test Component Tests and General Diagnostics. REPAIR the rear window defrost grid or INSTALL a new liftgate glass as necessary. REFER to Window Grid Wire Repair Window Grid Wire Repair or
Window Glass - Liftgate Service and Repair. TEST the system for normal operation.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
-------------------------------------------------
F5 CHECK CIRCUIT CRD06 (BN/YE) FOR AN OPEN
- Ignition OFF.
- Disconnect: Rear Window Defrost Relay.
- Measure the resistance between rear window defrost relay pin 5, circuit CRD06 (BN/YE), harness side and rear window defrost grid C402a-1, circuit CRD06 (BN/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to F6.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
-------------------------------------------------
F6 CHECK CIRCUIT CH122 (WH/OG) FOR AN OPEN
- Disconnect: HVAC Module C2357a or C2356a.
- Measure the resistance between HVAC module C2357a-3 or C2356a-3, circuit CH122 (WH/OG), harness side and rear window defrost relay pin 2, circuit CH122 (WH/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to F7.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
-------------------------------------------------
F7 CHECK CIRCUIT CH122 (WH/OG) FOR A SHORT TO GROUND
- Measure the resistance between rear window defrost relay pin 2, circuit CH122 (WH/OG), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to F8.
No
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
-------------------------------------------------
F8 CHECK CIRCUIT CH122 (WH/OG) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between rear window defrost relay pin 2, circuit CH122 (WH/OG), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR all DTCs. TEST the system for normal operation.
No
GO to F9.
-------------------------------------------------
F9 CHECK FOR CORRECT HVAC MODULE OPERATION
- Disconnect all the HVAC module connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all the HVAC 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 HVAC 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.
-------------------------------------------------