Pinpoint Test M : The TCU (TELEMATIC Control Unit Module) 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 Power Distribution for schematic and connector information.
Normal Operation and Fault Conditions

The TCU communicates on the HS-CAN4.

Possible Sources
- Fuse
- Wiring, terminals and connector
- TCU
Visual Inspection and Pre-checks
- Verify BCM fuse 8 (5A) is OK.

M1 CHECK THE HS-CAN4 (HIGH-SPEED CONTROLLER AREA NETWORK 4) TERMINATION RESISTANCE

Ignition OFF.

Disconnect negative battery cable.

Disconnect the diagnostic scan tool cable from the DLC.

Disconnect: GWM C2431.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2431-7	Courtesy of FORD MOTOR COMPANY	C2431-6

Is the resistance between 108 and 132 ohms?

Yes

GO to M3

GO to M2

M2 CHECK THE HS-CAN4 (HIGH-SPEED CONTROLLER AREA NETWORK 4) CIRCUITS BETWEEN THE TCU (TELEMATIC CONTROL UNIT MODULE) AND THE GWM (GATEWAY MODULE A) FOR AN OPEN

Disconnect: TCU C4803.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4803-8	Courtesy of FORD MOTOR COMPANY	C2431-7
C4803-16	Courtesy of FORD MOTOR COMPANY	C2431-6

Are the resistances less than 3 ohms?

Yes

GO to M5

No	REPAIR the circuit in question.

M3 CHECK THE TCU (TELEMATIC CONTROL UNIT MODULE) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4803-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to M4

No	VERIFY BCM fuse 8 (5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Introduction to identify the possible causes of the circuit short.

M4 CHECK THE TCU (TELEMATIC CONTROL UNIT MODULE) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4803-13	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to M5

No	REPAIR the circuit.

M5 CHECK FOR CORRECT TCU (TELEMATIC CONTROL UNIT MODULE) OPERATION

Ignition OFF.

Disconnect and inspect the TCU 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 TCU 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 TCU. REFER to: Telematics Control Unit (TCU) Module .

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.