Pinpoint Test C: The DC/DC Converter Does Not Operate Correctly
High-Voltage Converter/Inverter
Pinpoint Tests
Pinpoint Test C: The DC/DC Converter Does Not Operate Correctly
Refer to Wiring Diagram Set 12 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Charging System for schematic and connector information. Diagrams By Number
Normal Operation
The DC/DC converter is a liquid-cooled component that converts high voltage (216-397 volts) DC power to low voltage (12 volts) DC power while maintaining electrical isolation between the 2 DC power systems. The converter steps down the high voltage to 12 volts, providing power to the vehicle low voltage battery system. The PCM controls the operation of the DC/DC converter through an enable input from the PCM to the DC/DC converter.
This pinpoint test is intended to diagnose the following:
- PCM
- 12-volt battery
- Battery cables
- DC/DC converter
PINPOINT TEST C: THE DC/DC CONVERTER DOES NOT OPERATE CORRECTLY
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C1 CHECK THE PCM FOR DTCs
- Enter the following diagnostic mode on the scan tool: Self Test/Retrieve and Record On-Demand and Continuous Memory Diagnostic Trouble Codes (CMDTCs).
- Are any PCM DTCs present?
Yes
For DTC P1A0C only, GO to C2. For all other DTCs, REFER to Computers and Control Systems Information.
No
GO to C2.
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C2 CHECK THE INTEGRITY OF THE 12-VOLT BATTERY
- Ignition OFF.
- Refer to Battery and carry out Pinpoint Test A: Battery Condition Test to determine if the battery can hold a charge and is OK for use. Pinpoint Tests
- Did the battery pass the condition test?
Yes
GO to C3.
No
INSTALL a new 12-volt battery. REFER to Battery.
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C3 CHECK FOR CURRENT DRAINS
- Carry out the Battery - Drain Test. Refer to the Diagnosis and Testing subsection in Battery. Component Tests and General Diagnostics Testing and Inspection
- Are any circuits causing excessive current drains?
Yes
REPAIR as necessary. TEST the system for normal operation.
No
GO to C4.
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C4 CHECK THE VOLTAGE TO THE 12-VOLT BATTERY
- Start the engine.
- NOTE: The vehicle will start when the ignition switch is turned to the START position, but after a short period of time (approximately 2 minutes) the engine may shut down with the ignition switch still in the ON position. The DC/DC converter will output a normal charging rate with the engine running or not, but the engine MUST have run at least once. The state of charge of the High Voltage Traction Battery (HVTB) will have a direct affect on the length of engine running time.
- With the engine running (ignition switch ON, engine must have run at least once), monitor the voltage at the 12-volt battery.
- Is the voltage between 13.2-16.0 volts?
Yes
The system is operating correctly at this time. TEST the system for normal operation.
No
GO to C5.
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C5 CHECK THE POSITIVE 12-VOLT CABLE
- With the engine running (ignition switch ON, engine must have run at least once), headlights on high beam and the heater blower fan on high, measure the voltage drop between DC/DC converter positive C1457C, post side and 12-volt battery positive C1100A, post side.
- Is the voltage drop less than 0.75 volt?
Yes
GO to C6.
No
REPAIR or INSTALL a new 12-volt battery cable assembly as necessary. REFER to Battery. TEST the system for normal operation.
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C6 CHECK THE NEGATIVE 12-VOLT CABLE
- With the engine running (ignition switch ON, engine must have run at least once), headlights on high beam and the heater blower fan on high, measure the voltage drop between DC/DC converter negative C1457B, post side and DC/DC converter ground G105, ground bolt side.
- Is the voltage drop less than 0.25 volt?
Yes
GO to C7.
No
REPAIR or INSTALL a new 12-volt battery cable assembly as necessary. REFER to Battery. TEST the system for normal operation.
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C7 CHECK FOR CORRECT DC/DC CONVERTER OPERATION
- Disconnect all of the DC/DC converter connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all of the DC/DC converter connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new DC/DC converter. REFER to Direct Current/Direct Current (DC/DC) Converter . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
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