Pinpoint Test Ar : The TRM (Trailer Module) Does Not Respond To The Diagnostic Scan Tool

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.

AR1 CHECK THE TRM (TRAILER MODULE) VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect: TRM C2498A .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2498A-1	Courtesy of FORD MOTOR COMPANY	Ground
C2498A-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to AR2

No	VERIFY BJB fuse 30 (25A) or 43 (20A) is OK. If OK, REPAIR the circuit. If not OK, Refer to the Wiring Diagram Information to identify the possible causes of the circuit short.

AR2 CHECK THE TRM (TRAILER MODULE) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: TRM C2498B .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2498B-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to AR3

No	REPAIR the circuit.

AR3 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
C2498B-3	Courtesy of FORD MOTOR COMPANY	C2431-23
C2498B-2	Courtesy of FORD MOTOR COMPANY	C2431-22

Are the resistances less than 3 ohms?

Yes

GO to AR4

No	REPAIR the circuit in question.

AR4 CHECK FOR CORRECT TRM (TRAILER MODULE) OPERATION

Ignition OFF.

Disconnect and inspect the TRM 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. 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, General Service Bulletin (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, INSTALL a new 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.