Pinpoint Test B: DTC P0A94:4B

High-Voltage Converter/Inverter

Pinpoint Test B: DTC P0A94:4B

Refer to Wiring Diagram Set 12 (Fusion/Milan/MKZ, Fusion Hybrid, Milan Hybrid, MKZ Hybrid), Charging System for schematic and connector information. Diagrams By Number

Normal Operation

The DC to DC Converter Control Module (DC/DC) provides power for the low-voltage vehicle systems and charging of the 12-volt battery. The DC/DC can receive a High Speed Controller Area Network (HS-CAN) message from the PCM indicating that the Motor Electronics Cooling System (MECS) temperature exceeds 80°C (176°F). Because of this, the DC/DC may limit current output to 100 amps (maximum output is normally greater than 100 amps). When either condition is present, DTC P0A94:4B sets and the DC/DC will continue limiting current until the over-temperature condition clears. Periodic or constant heavy electrical loads of the 12-volt system may cause the 12-volt battery to become drained. Reduced functionality of 12-volt systems (headlamps, HVAC blower motor, etc.) may also be noticed.

- DTC P0A94:4B ( DC/DC Performance: Over Temperature) - Sets when the MECS temperature exceeds 80°C (176°F) and/or the DC/DC is limiting current output to 100 amps.

This pinpoint test is intended to diagnose the following:

- MECS
- DC/DC


PINPOINT TEST B: DTC P0A94:4B

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B1 CARRY OUT SELF-TEST OF THE PCM

- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self Test - PCM.
- Is PCM DTC P0A7C:00 reported?

Yes
REFER to Transaxle/Transmission Cooling - Hybrid Testing and Inspection to inspect and diagnose the MECS cooling loop circuit.

CLEAR the DTC. REPEAT the self-test. TEST the system for normal operation.

No
GO to B2.

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B2 CHECK FOR DC/DC DTC P0AF7:00

- Enter the following diagnostic mode on the scan tool: Self Test - DC/DC.
- Is DTC P0AF7:00 reported?

Yes
GO to Pinpoint Test C. Pinpoint Test C: DTC P0AF7:00

No
GO to B3.

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B3 CLEAR DTCs AND CARRY OUT SELF-TEST OF THE DC/DC

- Using the scan tool, clear the DC/DC DTCs.
- Enter the following diagnostic mode on the scan tool: Self Test - DC/DC.
- Is DTC P0A94:4B reported?

Yes
INSTALL a new DC/DC. REPEAT the self-test. TEST the system for normal operation.

No
Concern is not present at this time. CHECK the MECS coolant level. REFER to Transaxle/Transmission Cooling - Hybrid Motor Electronics Cooling System Draining and Filling. CLEAR the DTC. REPEAT the self-test. TEST the system for normal operation.

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