Pinpoint Test G : The OCSM Does Not Communicate With 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 will result in false resistance readings. Refer to Battery, Mounting and Cables .

G1 CHECK THE OCSM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect: OCSM C3159 .

Ignition ON.

Measure the voltage between:

Positive Lead		Negative Lead
Pin	Circuit	Pin	Circuit
C3159-1	CBX02 (BN/RD)	-	Ground

Courtesy of FORD MOTOR COMPANY

Is the voltage greater than 11 volts?

Yes	GO to G2.
No	VERIFY the BCM fuse 41 (7.5A) 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.

G2 CHECK THE OCSM GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: Negative Battery Cable.

Measure the resistance between:

Positive Lead		Negative Lead
Pin	Circuit	Pin	Circuit
C3159-14	GD901 (BK)	-	Ground

Courtesy of FORD MOTOR COMPANY

Is the resistance less than 3 ohms?

Yes	GO to G3.
No	REPAIR the circuit in question.

G3 CHECK THE HS-CAN CIRCUITS BETWEEN THE OCSM AND THE DLC FOR AN OPEN

Measure the resistance between:

Positive Lead		Negative Lead
Pin	Circuit	Pin	Circuit
C3159-18	VDB04 (WH/BU)	C251-6	VDB04 (WH/BU)
C3159-9	VDB05 (WH)	C251-14	VDB05 (WH)

Courtesy of FORD MOTOR COMPANY

Are the resistances less than 3 ohms?

Yes	CONNECT the negative battery cable. GO to G4.
No	REPAIR the circuit in question.

G4 CHECK FOR CORRECT OCSM OPERATION

Disconnect the OCSM connector.

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

Connect the OCSM connector and make sure it seats 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 OCSM. REFER to Supplemental Restraint System .
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.