Pinpoint Test Ai : The GFM (Generic Function Module) Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2018 Ford F-550 Super Duty, 2018 Ford F-450 Super Duty, 2018 Ford F-350 Super Duty, and 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

AI1 CHECK THE GFM (GENERIC FUNCTION MODULE) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: GFM C4321

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4321-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to AI2

No	VERIFY the BJB fuse 34 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Wiring Diagrams to identify the possible causes of the circuit short.

AI2 CHECK THE GFM (GENERIC FUNCTION MODULE) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4321-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to AI3

No	REPAIR the circuit.

AI3 CHECK THE MEDIUM SPEED CONTROLLER AREA NETWORK 2 (MS-CAN2) CIRCUITS BETWEEN THE GFM (GENERIC FUNCTION MODULE) AND THE GWM (GATEWAY MODULE A) FOR AN OPEN

Disconnect: GWM C2431

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4321-3	Courtesy of FORD MOTOR COMPANY	C2431-21
C4321-4	Courtesy of FORD MOTOR COMPANY	C2431-9

Are the resistances less than 3 ohms?

Yes

GO to AI4

No	REPAIR the circuit in question.

AI4 CHECK FOR CORRECT GFM (GENERIC FUNCTION MODULE) OPERATION

Ignition OFF.

Disconnect and inspect all the GFM connectors and related in-line connectors.

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

Reconnect the GFM connectors and related in-line 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 Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new GFM.

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.