Pinpoint Test Aa : The MRCMB (Movable Roof Control Module B) Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2020 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Module Communications Network for schematic and connector information. Refer to Convertible Top for schematic and connector information.
Normal Operation and Fault Conditions

The Moveable Roof Control Module B (MRCMB) communicates on the MS-CAN.

Possible Sources
- Fuse
- Wiring, terminals and connector
- MRCMB
Visual Inspection and Pre-checks
- Verify BJB fuse 15 (20A) is OK.

AA1 CHECK THE MOVEABLE ROOF CONTROL MODULE B (MRCMB) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: Moveable Roof Control Module B (MRCMB) C4831.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4831-6	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to AA2

No	VERIFY BJB fuse 15 (20A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Introduction to identify the possible causes of the circuit short.

AA2 CHECK THE MOVEABLE ROOF CONTROL MODULE B (MRCMB) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4831-3	Courtesy of FORD MOTOR COMPANY	Ground
C4831-5	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to AA3

No	REPAIR the circuit.

AA3 CHECK THE MS-CAN (MEDIUM SPEED-CONTROLLER AREA NETWORK) CIRCUITS BETWEEN THE MOVEABLE ROOF CONTROL MODULE B (MRCMB) AND THE GWM (GATEWAY MODULE A) FOR AN OPEN

Disconnect: GWM C2431.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4831-9	Courtesy of FORD MOTOR COMPANY	C2431-23
C4831-10	Courtesy of FORD MOTOR COMPANY	C2431-22

Are the resistances less than 3 ohms?

Yes

GO to AA4

No	REPAIR the circuit in question.

AA4 CHECK FOR CORRECT MOVEABLE ROOF CONTROL MODULE B (MRCMB) OPERATION

Ignition OFF.

Disconnect and inspect the Moveable Roof Control Module B (MRCMB) 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 Moveable Roof Control Module B (MRCMB) 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, 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 Moveable Roof Control Module B (MRCMB).

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.