Pinpoint Test F: DTC P0A27
High-Voltage Traction Battery
Pinpoint Tests
Pinpoint Test F: DTC P0A27
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 function may be triggered by an open condition in the front and/or rear Inertia Fuel Shutoff (IFS) switches, the high-voltage interlock circuit or the electrical interlock (EL I) circuit (fuse protected by the Battery Junction Box (BJB) fuse 26 [5A]). The IFS switch opens and causes the battery power off 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
-------------------------------------------------
F1 CHECK THE BCM DTCs
- Using the scan tool, clear the BCM DTCs.
- Cycle the ignition OFF then ON.
- Enter the following diagnostic mode on the scan tool: Self Test - BCM.
- Is DTC P0A1F also retrieved?
Yes
REFER to the Battery Control Module (BCM) DTC Chart to continue diagnosis of DTC P0A1F. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to F2.
-------------------------------------------------
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. If not OK, Refer to the Wiring Diagrams to identify the possible cause of the circuit short. Diagrams By Number
No
REPAIR circuit CBB26 (BU/WH). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------
F3 CHECK FOR CORRECT BCM OPERATION
NOTE: This pinpoint test step only addresses the 40-pin connector for the BCM. It is not necessary to disconnect the high-voltage connectors when following this pinpoint test step procedure.
- Check BCM electrical connector C4227A 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 Removal and Replacement. 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.
-------------------------------------------------