Pinpoint Test AF : The LTM Does Not Respond To The Scan Tool

WARNING: This page is about a different car, the 2018 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.

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

AF1 CHECK THE LTM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect: LTM C4174A .

Ignition ON.

Measure the voltage between:

Positive Lead		Negative Lead
Pin	Circuit	Pin	Circuit
C4174A-4	SBB07 (WH/RD)	-	Ground
C4174A-9	SBP08 (VT/RD)	-	Ground

Courtesy of FORD MOTOR COMPANY

Is the voltage greater than 11 volts?

Yes	GO to AF2.
No	VERIFY the BJB fuse 7 (30A) or BCM fuse 8 (10A) 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.

AF2 CHECK THE LTM GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: Negative Battery Cable.

Measure the resistance between:

Positive Lead		Negative Lead
Pin	Circuit	Pin	Circuit
C4174A-1	GD349 (BK/GY)	-	Ground

Courtesy of FORD MOTOR COMPANY

Is the resistance less than 3 ohms?

Yes	GO to AF3.
No	REPAIR the circuit.

AF3 CHECK THE MS-CAN CIRCUITS BETWEEN THE LTM AND THE DLC FOR AN OPEN

Disconnect: LTM C4174B .

Measure the resistance between:

Positive Lead		Negative Lead
Pin	Circuit	Pin	Circuit
C4174B-11	VDB06 (GY/OG)	C251-3	VDB06 (GY/OG)
C4174B-10	VDB07 (VT/OG)	C251-11	VDB07 (VT/OG)

Courtesy of FORD MOTOR COMPANY

Are the resistances less than 3 ohms?

Yes	GO to AF4.
No	REPAIR the circuit in question.

AF4 CHECK FOR CORRECT LTM OPERATION

Disconnect all the LTM connectors.

Repair:
- corrosion (replace connector or terminals - clean module pins)
- damaged or bent pins - replace terminals/pins
- pushed-out pins - replace pins as necessary

Connect all the LTM connectors and make sure they are seated correctly.

Operate the system and verify the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, discontinue this test and follow TSB instructions. If no TSBs address this concern, INSTALL a new LTM. REFER to Body Closures .
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.