Pinpoint Test F: DTC P0A27 - Hybrid Battery Power Off Circuit
High-Voltage Traction Battery
Pinpoint Tests
Pinpoint Test F: DTC P0A27 - Hybrid Battery Power Off Circuit
Refer to Wiring Diagram Set 12 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Charging System for schematic and connector information. Diagrams By Number
Normal Operation
With the engine running, the battery power off (BPO) function may be triggered by the front and/or rear Inertia Fuel Shutoff (IFS) switches opening, a high-voltage interlock circuit opening or the electrical interlock (EL I) circuit opening (fuse protected by the Battery Junction Box (BJB) fuse 26 [5A]). The IFS switch opens and causes the BPO mode to occur, no DTCs are set. Also, if the IFS switch is open, a power reset indicator in the Instrument Cluster (IC) illuminates.
- DTC P0A27 Hybrid Battery Power Off Circuit - the BCM will set this DTC if any of the following conditions are met:
- BCM detects a thermistor temperature greater than 57°C (134°F) for at least one second
- Contactor control is reported as closed while contactor status confirmed is reported as open for 10 seconds
- High Voltage Traction Battery (HVTB) is overheated.
This pinpoint test is intended to diagnose the following:
- Fuse
- Circuitry (to the PCM)
- HVTB
PINPOINT TEST F: DTC P0A27 - HYBRID BATTERY POWER OFF CIRCUIT
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F1 CHECK THE BCM DTCs
WARNING: Wear high-voltage insulated safety gloves and a face shield when working with high-voltage batteries or cables. The high-voltage insulated safety gloves should be of the appropriate safety and protection rating. Inspect the gloves before use and always wear them with the leather outer glove. Any hole in the rubber insulating glove is a potential entry point for high-voltage. Failure to follow these instructions may result in serious personal injury or death.
WARNING: Turn OFF the ignition switch for a minimum of 5 minutes before removing high-voltage cables. High-voltage cables and wiring are orange in color. The nominal high-voltage traction battery voltage (HVTB) is 330 V DC. Failure to follow these instructions may result in serious personal injury or death.
WARNING: Depower the high-voltage traction battery (HVTB) before carrying out any removal or installation procedures affecting the high-voltage battery system. Failure to follow this instruction may result in serious personal injury or death.
WARNING: When servicing the high-voltage system, establish a buffer zone per the specified procedure. Failure to follow this instruction may result in serious personal injury or death.
- Check the recorded BCM DTCs from the continuous and on-demand self tests.
- Is DTC P0A1F also retrieved?
Yes
REFER to the BCM DTC Chart to continue diagnosis of DTC P0A1F. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to F2.
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F2 CHECK THE EL I CIRCUIT CBB26 (BU/WH) FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: BJB Fuse 26 (5A).
- Disconnect: BCM C4227a.
- Measure the resistance between the output cavity of BJB fuse 26 (5A) and BCM C4227a-14, circuit CBB26 (BU/WH), harness side; and between the output cavity of BJB fuse 26 (5A) and ground.
- Is the resistance less than 5 ohms between the BJB and the BCM; and greater than 10,000 ohms between the BJB and ground?
Yes
VERIFY that the BJB fuse 26 (5A) is OK; if OK, GO to F3 .
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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F3 CHECK FOR CORRECT BCM OPERATION
NOTE: This pinpoint test step only addresses the 6-pin and 40-pin connectors for the BCM. It is not necessary to disconnect the high-voltage connectors when following this pinpoint test step procedure.
- Disconnect BCM electrical connector C4227a.
- Check for:
- corrosion.
- pushed-out pins.
- Connect BCM electrical connector C4227a and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVTB. REFER to High-Voltage Traction Battery High-Voltage Traction Battery. 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. CLEAR the DTCs. REPEAT the self-test.
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