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Pinpoint Test AQ: P1A4F:00

  1. NOTE: The Inverter System Controller (ISC) is referred to as the SOBDMC in the scan tool.

    Normal Operation and Fault Conditions 

    REFER to: Electric Powertrain Control - System Operation and Component Description .

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    SOBDMC P1A4F:00 High Voltage System Performance - High Voltage Disabled: No Sub Type Information This DTC sets when an open high voltage connector is detected within the first 100 miles of vehicle operation.

    Possible Causes 

    • Open service disconnect while vehicle is running
    • High voltage connections (between the high voltage battery and the front drive unit)
    • High voltage wiring, terminals or connectors

  2. AQ1 CHECK FOR BECM (BATTERY ENERGY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    • The ISC (SOBDMC) or BECM will always set an additional DTC to explain exactly which component on the high voltage bus has an issue. During the first 100 miles of vehicle operation, P1A4F is also enabled. P1A4F prevents further vehicle start attempts until the service tool procedure to "Reset The Secondary On-Board Diagnostic Control Module C" is run.
    • After "Reset The Secondary On-Board Diagnostic Control Module C" procedure is run, the DTC is cleared by: Command to clear codes, key off, wait 5 minutes, and then attempt to start the vehicle.

    • Ignition ON.

    • Using a diagnostic scan tool, perform the BECM self-test.

    Are any BECMDTC s present? 

    Yes  DIAGNOSE the BECMDTC s, REFER to: High Voltage Battery Charging System - Plug-In Hybrid Electric Vehicle (PHEV) .
    After the BECMDTC has been resolved, run service routine "Reset The Secondary On-Board Diagnostic Control Module C" followed by clearing of codes and a subsequent key cycle in order to allow P1A4F to clear.
    No  GO to  AQ2

  3. AQ2 CHECK FOR INVERTER SYSTEM CONTROLLER (ISC) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Ignition ON.

    • Using a diagnostic scan tool, clear all Diagnostic Trouble Codes (DTCs) from the Inverter System Controller (ISC).

    • Ignition OFF.

    • Wait 5 minutes.

    • Ignition ON.

    • Using a diagnostic scan tool, check for CMDTC s Inverter System Controller (ISC).

    Are any Inverter System Controller (ISC) DTC s other than P1A4F present? 

    Yes  DIAGNOSE all other Inverter System Controller (ISC) DTC s, REFER to the DTC chart in This Service Information.After the SOBDMCDTC has been resolved, run service routine "Reset The Secondary On-Board Diagnostic Control Module C" followed by clearing of codes and a subsequent key cycle in order to allow P1A4F to clear.
    No  For DTC P1A4F only, GO to  AQ3

  4. AQ3 VISUAL INSPECTION OF THE HIGH VOLTAGE SYSTEM

    • Ignition OFF.

    • Remove the Inverter System Controller (ISC) side cover. When removing side cover, pull cover straight out approximately 2 inches before moving upwards or damage to the high voltage interlock connector may occur. REFER to: Inverter System Controller [SOBDMC] .
      GFD828932Courtesy of FORD MOTOR COMPANY

    • Examine all the high voltage connections for damage and loose or broken conditions.

    • Verify the high voltage terminal bolts are fully seated and torqued to 12 Nm
      GFD828933Courtesy of FORD MOTOR COMPANY

    Is a concern present? 

    Yes  REPAIR as necessary. CLEAR the Inverter System Controller (ISC) DTC s and REPEAT the self-test.
    No  GO to  AQ4

  5. AQ4 VERIFY THE HIGH VOLTAGE TRACTION BATTERY STATE OF CHARGE

    • Connect all previously disconnected connectors.

    • Ignition ON.

    Access the SOBDMC and monitor the HVBAT_V (V) PID

    Is the voltage greater than 170 volts for HEV or 250 volts for PHEV ' 

    Yes  GO to  AQ5
    No  CHARGE the high voltage traction battery. REFER to: High Voltage System De-energizing .
    CLEAR the Inverter System Controller (ISC) DTC s. REPEAT the self-test.

  6. AQ5 VERIFY CONCERN IS PRESENT

    • Clearing the Inverter System Controller (ISC) Diagnostic Trouble Codes (DTCs) will erase any Inverter System Controller (ISC) recorded freeze frame data. Make sure to record any Inverter System Controller (ISC) freeze frame information before proceeding any further. Refer to the scan tool instruction manual for freeze frame Parameter Identification (PID) menu.
    • Just clearing codes is not expected to clear P1A4F. It is necessary to use Routine "Reset The Secondary On-Board Diagnostic Control Module C" followed by clearing of codes and a subsequent key cycle to clear the P1A4F.

    • Use Routine "Reset The Secondary On-Board Diagnostic Control Module C" in the service tool to enable clearing of the code. CLEAR the Inverter System Controller (ISC) DTC s.

    • Ignition OFF.

    • Wait 5 minutes.

    • Ignition ON.

    • CARRY out the Inverter System Controller (ISC) self-test.

    Is DTC P1A4F present? 

    Yes  GO to  AQ6
    No  The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

  7. AQ6 CHECK THE HIGH VOLTAGE CABLES FOR AN INTERMITTENT CONCERN

    • Ignition OFF.

    • Disconnect and inspect all the High Voltage Battery connectors.

    • Disconnect and inspect all the Inverter System Controller (ISC) 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 High Voltage Battery connectors. Make sure they seat and latch correctly.

    • Reconnect the Inverter System Controller (ISC) connectors. Make sure they seat and latch correctly.

    • Ignition ON.

    Access the SOBDMC and monitor the M_INV_V (V) PID

    • Carefully wiggle all accessible wiring and connectors associated with the High Voltage Cable from the Inverter System Controller (ISC) to the Traction Battery, and look for a change in the PID state.

    Is a concern present during the wiggle test? 

    Yes  REPAIR as necessary. Following wiring repair, use Routine "Reset The Secondary On-Board Diagnostic Control Module C" in the service tool followed by clearing of codes and a subsequent key cycle to clear the P1A4F.
    No  The system is operating correctly at this time, the concern may have been caused by a loose or corroded connector.
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