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Pinpoint Test AF : P0C79

  1. NOTE: The Inverter System Controller (ISC) is referred to as the SOBDMC (Secondary On-Board Diagnostic Control Module C) 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 P0C79:00 Drive Motor "A" Inverter Voltage Too High: No Sub Type Information This DTC sets when an overvoltage event has occurred in the module.

    Possible Sources 

    • Other Inverter System Controller (ISC) DTCs
    • Loose high voltage cables
    • Service disconnect not connected
    • Wiring, terminals or connectors

  2. AF1 CHECK THE BECM (BATTERY ENERGY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

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

    Are there any BECM DTCs? 

    Yes  DIAGNOSE and REPAIR any BECM DTCs. REFER to: High Voltage Battery, Mounting and Cables - Hybrid Electric Vehicle (HEV) .
    No  GO to  AF2

  3. AF2 CHECK THE INVERTER SYSTEM CONTROLLER (ISC) CONTINUOUS MEMORY DIAGNOSTIC CODES (CMDTCS)

    • Using a diagnostic scan tool, check for CMDTCs

    Was P0C79 the only CMDTC stored in the Inverter System Controller (ISC)? 

    Yes  GO to  AF3
    No  DIAGNOSE and REPAIR any Inverter System Controller (ISC) DTCs. REFER to Diagnostic Trouble Code (DTC) Chart .

  4. AF3 VERIFY THE HIGH VOLTAGE TRACTION BATTERY STATE OF CHARGE

    • Ignition ON.

    • Access the SOBDMC and monitor the HVBAT_V (V) PID

    Is the voltage greater than 250 volts? 

    Yes  GO to  AF4
    No  CHARGE the high voltage traction battery. REFER to: High Voltage Battery Charging - Hybrid Electric Vehicle (HEV) . CLEAR the Inverter System Controller (ISC) DTCs. REPEAT the self-test.

  5. AF4 VERIFY CONCERN IS PRESENT

    NOTE: 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.

    • Ignition ON.

    • CLEAR the Inverter System Controller (ISC) DTCs.

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

    Is DTC P0C79 present? 

    Yes  GO to  AF5
    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.

  6. AF5 CHECK THE HIGH VOLTAGE CABLES FOR AN INTERMITTENT CONCERN

    • Ignition OFF.

    • Disconnect and inspect all the High Voltage Battery Junction Box 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 Junction Box connectors. Make sure they seat and latch correctly.

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

    • 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] .

    • 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 8 lb.ft (10.5 Nm)

    • Ignition ON.

    • Access the SOBDMC and monitor the GEN_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.
    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.
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