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

WARNING: This page is about a different car, the 2022 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

Refer to MODULE COMMUNICATIONS NETWORK for schematic and connector information. Refer to TRAILER/CAMPER ADAPTER for schematic and connector information.
Normal Operation and Fault Conditions

The TRM communicates with the diagnostic scan tool through the MS-CAN.

Possible Sources
- Fuse
- Wiring, terminals and connector
- TRM
Visual Inspection and Pre-checks
- Verify BJB fuses 73 (30A) and 87 (40A) are OK.

T1 CHECK THE TRM (TRAILER MODULE) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: TRM C2498A.

Ignition ON.

Measure:

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

Is the voltage greater than 11 volts?

Yes

GO to T2

No	VERIFY BJB fuses 73 (30A) and 87 (40A) are OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM ELECTRICAL WIRING DIAGRAM INTRODUCTION to identify the possible causes of the circuit short.

T2 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 T3

No	REPAIR the circuit.

T3 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 T4

No	REPAIR the circuit in question.

T4 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. 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.