Pinpoint Test A : The Defrost System Is Inoperative

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

A1 CHECK THE REAR WINDOW DEFROST FUSE
- Ignition OFF.
- Inspect the BJB fuse 99 (40A).
Is the fuse OK?

Yes GO to A2

No Refer to the Wiring Diagram Information to identify the possible causes of the circuit short.

A2 CHECK THE REAR WINDOW DEFROST GRID VOLTAGE

Ignition OFF.

Disconnect: Heated Rear Window Element C402A .

Start the engine.

Activate the rear window defrost switch.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C402A-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to A3

No	VERIFY the BJB fuse 99 (40A). If not OK, Refer to the Wiring Diagram Information to identify the possible causes of the circuit short. If OK, GO to A4

A3 CHECK THE REAR WINDOW DEFROST GRID GROUND

Ignition OFF.

Disconnect: Heated Rear Window Element C402B .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C402B-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes	CARRY OUT the Grid Wire Test. REFER to Grid Wire Test. REPAIR the rear window defrost grid, INSTALL a new liftgate window glass assembly if necessary. REFER to: Heated Window Grid Wire Repair . REFER to:Liftgate Window Glass .

No	REPAIR the circuit.

A4 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR VOLTAGE

Ignition OFF.

Disconnect: FCIM C2402A .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2402A-7	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to A5

GO to A6

A5 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect: BJB C1035C .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2402A-7	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	Refer to the Wiring Diagram Information to identify the possible causes of the circuit short.

GO to A7

A6 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: BJB C1035C .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2402A-7	Courtesy of FORD MOTOR COMPANY	C1035C-21

Is the resistance less than 3 ohms?

Yes	INSTALL a new BJB.

No	REPAIR the circuit.

A7 CHECK THE REAR WINDOW DEFROST RELAY OPERATION

Connect: BJB C1035C .

NOTE: If the jumper wire fuse blows when it is connected, Refer to the Wiring Diagram Information to identify the possible causes of the circuit short to voltage.

Connect a fused jumper wire:

Positive Lead	Measurement / Action	Negative Lead
C2402A-7	Courtesy of FORD MOTOR COMPANY	Ground

Measure:

Positive Lead	Measurement / Action	Negative Lead
C402A-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	REMOVE the fused jumper wire. GO to A9

No	REMOVE the fused jumper wire. GO to A8

A8 CHECK THE REAR WINDOW DEFROST RELAY OUTPUT CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1035D-49	Courtesy of FORD MOTOR COMPANY	C402A-1

Is the resistance less than 3 ohms?

Yes	INSTALL a new BJB.

No	REPAIR the circuit.

A9 CHECK FOR CORRECT FCIM (FRONT CONTROLS INTERFACE MODULE) OPERATION

Ignition OFF.

Disconnect and inspect all the FCIM connectors.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins as necessary
- pushed-out pins - install new pins as necessary

Reconnect the FCIM connectors and all previously disconnected rear window defrost system connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes

CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, FCIM guided routine is not applicable for this vehicle and market. Replace the component that was faulted through service information diagnosis.

No	The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.