Eaton Fuller Hybrid Transmission Fault Code 120 – APG Unit 1 AC Voltage
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. It generates 60 Hz single-phase 120 volts AC power for utility applications.
Fault Code 120 – APG Unit 1 AC Voltage 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 3 is set when output voltage is detected to be greater than or equal to 145 volts AC power.
- FMI 4 is set when output voltage is detected to be less than or equal to 75 volts AC power.
Fallback When Fault Code 120 is set the following conditions occur:
- Amber “Check Hybrid” light illuminates.
- APG shuts down.
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 3
- FMI 4
- Short phase to neutral in harness
- Power Panel
- Potential of output device like motor causing surge