Pinpoint Test G: The Defrost System Is Inoperative
WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- G1 CHECK THE POWER TO THE HEATED REAR WINDOW RELAY
- Disconnect: Heated Rear Window Relay
- Key in ON position.
- Measure the voltage between heated rear window relay socket pin 86 harness side and ground; and between pin 30 harness side and ground.
- Is the voltage greater than 10 volts?
- YES : Go to G2.
- NO : VERIFY the CJB fuses 13 (10A) and 114 (40A) are OK. If OK, REPAIR the circuit(s). TEST the system for normal operation.
- G2 CHECK THE IC OUTPUT
- Turn on the rear window defrost.
- Measure the voltage between heated rear window relay socket pin 85 and pin 86 harness side.
- Is the voltage greater than 10 volts?
- G3 CHECK THE HEATED REAR WINDOW RELAY
- Carry out the Heated Rear Window Relay Component Test. Refer to COMPONENT TESTING.
- Did the heated backlight relay pass the component test?
- YES : Go to G4.
- NO : INSTALL a new heated rear window relay. TEST the system for normal operation.
- G4 CHECK THE REAR WINDOW DEFROST GRID VOLTAGE
- Connect: Heated Rear Window Relay
- Disconnect: Rear Window Defrost Grid Power C3241A
- Key in ON position.
- Turn rear window defrost ON.
- Measure the voltage between rear window defrost grid power C3241A-1, circuit 186 (BN/LB) and ground.
- Is the voltage greater than 10 volts?
- YES : Go to G5.
- NO : REPAIR the circuit. TEST the system for normal operation.
- G5 CHECK THE REAR WINDOW DEFROST GRID GROUND
- Key in OFF position.
- Disconnect: Rear Window Defrost Grid Ground C3241B
- Measure the resistance between rear window defrost grid ground C3241B-1, circuit 57 (BK) and ground.
- Is the resistance less than 5 ohms?
- YES : REPAIR the rear window defrost grid or INSTALL a new rear window glass. REFER to Window Grid Wire Repair or Window Glass - Rear in this article. TEST the system for normal operation.
- NO : REPAIR the circuit. TEST the system for normal operation.
- G6 CHECK THE REAR WINDOW DEFROST SWITCH
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Monitor the IC PID RDEF_SW while pressing and releasing the rear window defrost switch.
- Does the PID agree with the rear window defrost switch position?
- G7 CHECK CIRCUIT 1009 (OG/YE) FOR AN OPEN
- Disconnect: IC C220b
- Measure the resistance between IC C220b-6, circuit 1009 (OG/YE) and rear window defrost relay socket pin 85, circuit 1009 (OG/YE) harness side.
- Is the resistance less than 5 ohms?
- YES : INSTALL a new IC. REFER to INSTRUMENT CLUSTER article. TEST the system for normal operation.
- NO : REPAIR the circuit. TEST the system for normal operation.
- G8 CHECK CIRCUIT 1010 (DB/OG) FOR AN OPEN
- Disconnect: IC C220a
- Disconnect: HVAC Module - Electronic Automatic Temperature Control (EATC) C228a or HVAC Module - Electronic Manual Temperature Control (EMTC) C294a
- Measure the resistance between IC C220a-8, circuit 1010 (DB/OG) and HVAC module - EATC C228a-10 or HVAC module - EMTC C294a-10, circuit 1010 (DB/OG) harness side.
- Is the resistance less than 5 ohms?
- YES : INSTALL a new HVAC module - EATC or HVAC module - EMTC. REFER to CLIMATE CONTROL article. TEST the system for normal operation.
- NO : REPAIR the circuit. TEST the system for normal operation.