Eaton Fuller Hybrid Transmission Fault Code 125 – APG Unit 1 Over Temperature
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 connected to the high-voltage DC bus of the Eaton hybrid electric vehicle system. It generates 60 Hz single-phase 120V AC power for utility applications. Fault Code 125 sets when the heat sink temperature exceeds the upper-temperature limit for normal operation.
Fault Code 125 – APG Unit 1 Over Temperature 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 0 is set when the heat sink temperature at an unspecified module exceeds the upper-temperature limit for normal operation.
Fallback When Fault Code 125 is set the following conditions occur:
- Amber “Check Hybrid” light illuminates.
- Fault is stored in Hybrid Control Module (HCM) memory.
- APG shuts down if operating.
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 0
- Cooling System
- APG Temperature Sensor fault in range