Eaton Fuller Hybrid Transmission Fault Code 126 – APG Unit 1 Configuration

Fault code for Eaton Hybrid Drive Systems models (MY08) EH-8E306A-U, EH-8E306A-UPG, EH-8E306A-UP, EH-8E306A-CD, EH-8E306A-T, EH-6E606B-CD, (MY09) EH-8E406A-U/P, EH-8E406A-UP, EH-8E406A-UPG, EH-8E406A-CD, EH-8E406A-CDG, EH-8E406A-CDR, EH-8E406A-T, EH-6E706B-CD, EH-6E706B-P and EH-6E706B-UPG. Read below to learn how to test, clear and fix fault code errors for your Freightliner, Mack, Peterbilt, Kenworth, Volvo, International, and heavy-duty truck and equipment. The Auxiliary Power Generator (APG) is a 5kW/5kVA DC/AC Inverter that is connected to the high-voltage DC bus of the Eaton Hybrid electric vehicle system, and generates 60 Hz single-phase 120V AC power for utility applications.

Fault Code 126 – APG Unit 1 Configuration Detection

The following preconditions must be met before the system detects the fault:

  • APG Inverter needs to be operating.

Note: When troubleshooting an Inactive code refer to the Product Diagnostic Mode (PDM)

Conditions to Set Fault Code Active

  • FMI 2 is set whenever DC/DC voltage feedback signal reads greater than 15 volts or less than 10 volts and ePTO mode is engaged.
  • FMI 4 is set if the voltage feedback is less than 15 volts and greater than 10 volts and the difference between the voltage feedback and the vehicle battery voltage is greater than 0.5 volts for 1 second or more.

Fallback When Fault Code 126 is set the following conditions occur:

  • FMI 22 is set when a control board self test has failed. (MY08)
  • FMI 23 is set when a nonvolatile data checksum failure has occurred. (MY08)
  • FMI 24 is set when software incompatibility has been detected. (MY08)
  • FMI 25 is set when a blown fuse is detected.
  • FMI 26 is set when the internal fan speed is detected to be low.
  • FMI 27 is set when there is an Inverter fault.

Conditions to Set Fault Code Inactive

Only Inactive faults can be cleared from the Transmission Electronic Control Unit (TECU) or HCM history using ServiceRanger. The TECU automatically clears the faults from history after 200 hours and the HCM automatically clears the faults from history after the fault has been Inactive for 200 hours.

This fault code can be caused by any of the following:

  • FMI 22 – 27
    • APG

Fault Code 126 – APG Unit 1 Configuration Test

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