Pinpoint Test AJ : The TELEMATIC Control Unit (TCU) Module Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2015 Lincoln MKZ. However, it is still accessible from the selected car via links, so may be relevant.

AJ1 CHECK THE TCU (TELEMATIC CONTROL UNIT MODULE) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: TCU C4803 .

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 AJ2

No	VERIFY BCM fuse 10 (5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction (Hybrid) to identify the possible causes of the circuit short.

AJ2 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 AJ3

No	REPAIR the circuit.

AJ3 CHECK THE HS-CAN3 (HIGH SPEED-CONTROLLER AREA NETWORK 3) CIRCUITS BETWEEN THE TCU (TELEMATIC CONTROL UNIT MODULE) AND THE GWM (GATEWAY MODULE A) FOR AN OPEN

Disconnect: GWM C2431 .

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4803-8	Courtesy of FORD MOTOR COMPANY	C2431-16
C4803-16	Courtesy of FORD MOTOR COMPANY	C2431-15

Are the resistances less than 3 ohms?

Yes

GO to AJ4

No	REPAIR the circuit in question.

AJ4 CHECK FOR CORRECT TCU (TELEMATIC CONTROL UNIT MODULE) OPERATION

Ignition OFF.

Disconnect and inspect the TCU 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 TCU 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 Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new TCU. For touchscreen display, REFER to: Telematics Control Unit (TCU) Module . For THX ® audio system, 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.