Pinpoint Test F: B1863

NOTE: A trailer must be connected for this DTC to set.

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

Normal Operation and Fault Conditions

The TBM receives battery and ignition voltage from AJB fuses 71 (30A) and 50 (10A). The TBM has a single ground circuit.

An open circuit in the wiring or a condition that results in an open in the ground circuit, such as an internal failure of the TBM or a connector concern, results in the TBM setting this DTC. When this DTC sets, the TBM disables trailer braking and sends a TBC FAULT message to the message center. If a trailer is not connected to the vehicle when this DTC sets, the TBM sends a TRAILER BRAKE MODULE FAULT message to the message center.

DTC Fault Trigger Conditions
- DTC Fault Trigger Conditions
- TBM B1863 -- Ground ECU Circuit Open
  - This DTC sets in continuous memory and on-demand when the TBM detects a rise in battery voltage after turning off the trailer brake output.
Possible Sources
- Wiring, terminals or connectors
- TBM
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

F1 CHECK THE TBM (TRAILER BRAKE CONTROL MODULE) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect TBM C307.

Disconnect the battery negative cable. REFER to: BATTERY DISCONNECT AND CONNECT - VEHICLES WITH: SINGLE BATTERY or BATTERY DISCONNECT AND CONNECT - VEHICLES WITH: DUAL BATTERIES .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C307-3	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to F2

No	LOCATE and INSPECT the ground circuit eyelet. Refer to TRAILER/CAMPER ADAPTER for schematic and connector information. DISCONNECT and CLEAN the ground circuit eyelet as necessary. If the ground circuit eyelet is OK, REPAIR the circuit.

F2 CHECK FOR CORRECT TBM (TRAILER BRAKE CONTROL MODULE) OPERATION

Inspect TBM C307.

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

Connect TBM C307 and make sure that it seats correctly.

Connect the battery negative cable. REFER to: BATTERY DISCONNECT AND CONNECT - VEHICLES WITH: SINGLE BATTERY or BATTERY DISCONNECT AND CONNECT - VEHICLES WITH: DUAL BATTERIES .

Operate the system and verify 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 the TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new TBM. REFER to: Trailer Brake Control Module (TBM) .

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.