Pinpoint Test H: B148B:2A, B148B:49, B148C:2A Or U064D:08

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Refer to TRAILER/CAMPER ADAPTER for schematic and connector information.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
TBM U064D:08	Lost Communication with Trailer Brake Control Switch: Bus Signal/Message Failures	This DTC sets when there is a lost LIN communication with the trailer brake switch.
TBM B148B:2A	Trailer Brake Manual Slider: Stuck in Range	This DTC sets when the manual slider switch is applied in a fixed, active position for more than 5 minutes.
TBM B148B:49	Trailer Brake Manual Slider: Internal Electronic Failure	This DTC sets when the manual slider is shorted to TRM circuit ground for 1 second.
TBM B148C:2A	Trailer Brake Gain Button: Stuck in Range	This DTC sets when either gain button is pressed for more than 2 minutes.

Possible Sources

Wiring, terminals or connectors
TRM
Trailer Tow Switch
Obstructions or foreign material

H1 VERIFY TBM (TRAILER BRAKE CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

NOTE: The TRM is a combined TBM and Trailer Lighting Module.

Ignition ON.

Using a diagnostic scan tool, carry out the TBM self-test.

Clear the Diagnostic Trouble Codes (DTCs).

Operate the manual slider switch twice.

Using a diagnostic scan tool, carry out the TBM self-test.

Is DTC B148B:2A, B148B:49, B148C:2A or U064D:08 present?

Yes	For DTC U064D:08, GO to H2 For DTC B148B:2A, B148B:49 or B148C:2A, GO to H5

No	If no Diagnostic Trouble Codes (DTCs) return, the concern may have been caused by something laying on or against the manual slider switch INFORM the customer of the manual slider switch fault setting condition as stated above..

H2 CHECK THE TRAILER BRAKE CONTROL SWITCH LIN CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect TRM C2498C.

Disconnect Trailer Brake Control Switch C2830.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2498C-10	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

GO to H3

H3 CHECK THE TRAILER BRAKE CONTROL SWITCH LIN CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2498C-10	Courtesy of FORD MOTOR COMPANY	C2830-2

Is the resistance less than 3 ohms?

Yes

GO to H4

No	REPAIR the circuit.

H4 CHECK THE TRAILER BRAKE CONTROL SWITCH LIN CIRCUIT FOR A SHORT TO GROUND

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2498C-10	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to H5

No	REPAIR the circuit.

H5 CHECK FOR CORRECT TRM (TRAILER MODULE) OPERATION

Disconnect TRM C2498C (if not previously disconnected).

Using a good light source, inspect the connector for the following:
- corrosion - install new connector or terminal and clean the module pins
- damaged or bent pins - install new terminals or pins
- pushed-out pins - install new pins as necessary
- spread terminals - install new terminals as necessary

Connect TRM C2498C, make sure it seats and latches correctly.

Connect Trailer Brake Control Switch C2830.

Operate the system and verify 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, INSTALL a new TRM module. REFER to: Trailer Module (TRM) .

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