PINPOINT TEST AA : The Trailer Brake Control (TBC) Module Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2016 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables .

AA1 CHECK THE TBC MODULE VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: TBC module C2142 .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2142-8	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	GO to AA2.
No	VERIFY BJB fuse 18 (30A) is 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.

AA2 CHECK THE TBC MODULE GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: Negative Battery Cable.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2142-3	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes	GO to AA3.
No	REPAIR the circuit.

AA3 CHECK THE HS-CAN CIRCUITS BETWEEN THE TBC MODULE AND THE DLC FOR AN OPEN

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2142-10	Courtesy of FORD MOTOR COMPANY	C251-6
C2142-11	Courtesy of FORD MOTOR COMPANY	C251-14

Are the resistances less than 3 ohms?

Yes	CONNECT the negative battery cable. GO to AA4.
No	REPAIR the circuit in question. CONNECT the negative battery cable.

AA4 CHECK FOR CORRECT TBC MODULE OPERATION

Ignition OFF.

Disconnect and inspect the TBC module connector 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 TBC module connector and related in-line connectors. Make sure they seat and latch correctly.

Operate the system and determine the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any applicable TSBs. If a TSB DISCONTINUE this test and FOLLOW TSB instructions. If no TSBs address this concern, INSTALL a new TBC module. REFER to Auxiliary Brake System .
No	The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.