Pinpoint Test AE : The TRM (Trailer 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.

AE1 CHECK THE TRM (TRAILER MODULE) VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect: TRM C2496A .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2496A-1	Courtesy of FORD MOTOR COMPANY	Ground
C2496A-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to AE2

No	VERIFY BJB fuses 42 (40A) and 65 (30A) are OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Wiring Diagrams to identify the possible causes of the circuit short.

AE2 CHECK THE TRM (TRAILER MODULE) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: TRM C2496B

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2496B-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to AE3

No	REPAIR the circuit.

AE3 CHECK THE MS-CAN (MEDIUM SPEED-CONTROLLER AREA NETWORK) CIRCUITS BETWEEN THE TRM (TRAILER MODULE) AND THE GWM (GATEWAY MODULE A) FOR AN OPEN

Disconnect GWM C2431 .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2496B-3	Courtesy of FORD MOTOR COMPANY	C2431-23
C2496B-2	Courtesy of FORD MOTOR COMPANY	C2431-22

Are the resistances less than 3 ohms?

Yes

GO to AE4

No	REPAIR the circuit in question.

AE4 CHECK FOR CORRECT TRM (TRAILER MODULE) OPERATION

Ignition OFF.

Disconnect and inspect the TRM 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 TRM 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 TRM. Refer to: Trailer Module (TRM) .

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.