Pinpoint Test H: U012F And U044D

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Wiring Diagrams Charging System for schematic and connector information.

Normal Operation and Fault Conditions

The charging system supplies voltage to the battery and the vehicle electrical system through the battery B+ cable. The PCM monitors the generator output through a LIN communication circuit. The PCM uses this LIN circuit to communicate the desired voltage setpoint to the generator internal voltage regulator. The generator also uses this to communicate the generator load and error conditions to the PCM.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PCM U012F:00	Lost Communication With Generator "B" Control Module: No Sub Type Information	Sets if the PCM does not detect communication through the LIN circuit. This can be a result of an open or short in the LIN circuit. This DTC also sets if the generator B+ circuit is open.
PCM U044D:00	Invalid Data Received From Generator "B" Control Module: No Sub Type Information	Sets when the PCM receives via DC/ AC inverter invalid data from the generator.

Possible Sources

DC/ AC inverter
Generator
PCM
Wiring, terminals or connectors

Visual Inspection and Pre-checks

Inspect high current BJB for loose, damaged or corroded connections.
Inspect the BJB fuse 201 (300A).
Inspect the BJB fuse 25 (10A).
Inspect the FEAD belt.
Inspect the battery monitoring sensor.

NOTE: Make sure battery voltage is greater than 24 volts prior to and during this pinpoint test.
NOTE: Do not have a battery charger attached during vehicle testing.

H1 COMPARE THE GENERATOR B+ CIRCUIT TO BATTERY VOLTAGE

Measure and record:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1251B-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage within 0.5 volt of the recorded battery voltage?

Yes

GO to H2

TIGHTEN or INSTALL a new generator B+ nut as needed. REFER to: Generator - 3.3L Duratec-V6 . REFER to: Generator - 5.0L 32V Ti-VCT . VERIFY high current BJB fuse 201 (300A) 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.

H2 CHECK THE GENERATOR LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect secondary generator C1251A.

Disconnect DC/ AC inverter C3501C.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1251A-2	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

GO to H3

H3 CHECK THE GENERATOR LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.

Measure and record:

Positive Lead	Measurement / Action	Negative Lead
C1251A-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to H4

No	REPAIR the circuit.

H4 CHECK THE GENERATOR LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1251A-2	Courtesy of FORD MOTOR COMPANY	C3501C-6

Is the resistance less than 3 ohms?

Yes	INSTALL a new generator. REFER to: Generator - 3.3L Duratec-V6 . REFER to: Generator - 5.0L 32V Ti-VCT . REPEAT the PCM self-test. If DTC U012D is retrieved again, GO to H5

No	REPAIR the affected circuit.

H5 CHECK FOR CORRECT DC (DIRECT CURRENT) / AC (ALTERNATING CURRENT) INVERTER OPERATION

Ignition OFF.

Disconnect and inspect all DC/ AC inverter 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 DC/ AC inverter 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 the TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, Refer to PCM GUIDED ROUTINE TESTING
Internet Explorer version 11 or greater is required to perform this Pinpoint Test.

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.