Pinpoint Test I : The DCMR (Differential Control Module Rear) Does Not Respond To The Diagnostic Scan Tool

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

I1 CHECK THE DCMR (DIFFERENTIAL CONTROL MODULE REAR) VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect: DCMR C3396 .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C3396-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to I3

No	VERIFY BJB fuse 54 (40A) is OK. If OK, GO to I2. If not OK, Refer to the Wiring Diagram Information to identify the possible causes of the circuit short.

I2 CHECK THE DIFFERENTIAL CONTROL RELAY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: BJB C1035D .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1035D-4	Courtesy of FORD MOTOR COMPANY	C3396-1

Is the resistance less than 3 ohms?

Yes

GO to I6

No	REPAIR the circuit.

I3 CHECK THE DCMR (DIFFERENTIAL CONTROL MODULE REAR) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C3396-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to I4

No	REPAIR the circuit.

I4 CHECK THE HS-CAN1 (HIGH-SPEED CONTROLLER AREA NETWORK 1) CIRCUITS BETWEEN THE DCMR (DIFFERENTIAL CONTROL MODULE REAR) AND THE DLC (DATA LINK CONNECTOR) FOR AN OPEN

Measure:

Positive Lead	Measurement / Action	Negative Lead
C3396-14	Courtesy of FORD MOTOR COMPANY	C251-6
C3396-15	Courtesy of FORD MOTOR COMPANY	C251-14

Are the resistances less than 3 ohms?

Yes

GO to I5

No	REPAIR the circuit in question.

I5 CHECK FOR CORRECT DCMR (DIFFERENTIAL CONTROL MODULE REAR) OPERATION

Ignition OFF.

Disconnect and inspect the DCMR connector.

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 DCMR connector. Make sure it seats and latches correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes

CHECK OASIS for any applicable service articles: TSB, General Service Bulletin (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 DCMR. REFER to: Differential Control Module Rear (DCMR) .

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

I6 CHECK FOR CORRECT BJB (BATTERY JUNCTION BOX) OPERATION

Ignition OFF.

Disconnect and inspect the BJB 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 BJB connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes

CHECK OASIS for any applicable service articles: TSB, General Service Bulletin (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 BJB. The differential control relay is not serviceable.

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