Eaton Fuller Hybrid Transmission Fault Code 27 – Clutch Disengagement

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 mechanical clutch assembly is controlled through the Electric Clutch Actuator (ECA) that is mounted on the clutch housing. The Hybrid Control Module (HCM) controls the ECA position and monitors several variables to determine if there is a slip concern in the clutch when it is in the closed position.

Fault Code 2 – Motor / Generator Temperature Sensor Detection

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

  • HCM ignition voltage is greater than 7 volts and less than 16 volts.
  • ECA ignition voltage is greater than 7 volts and less than 16 volts.

Conditions to Set Fault Code Active

  • FMI 7 is set when the engine torque is greater than 400 N*m, engine torque commanded is less than 0 for 0.3 seconds and the clutch position commanded is open for 1 second with the gear position confirmed in neutral. Or, if the clutch input speed is greater than 300 RPM, the clutch output speed is greater than 300 RPM, the clutch is commanded open for 1 second, and the selected gear is neutral with everything above being true for 10 seconds.
  • FMI 13 is set when the ECA fails to calibrate during power up due to a mechanical binding issue and there are no other ECA faults present.
  • FMI 14 is set when the HCM has commanded the ECA to disengage the clutch and the Input Shaft Speed is greater than 315 RPM for more than 11 seconds with the transmission in neutral and the engine running.

Fallback When Fault Code 2 is set the following conditions occur:

  • Red “Stop Hybrid” light illuminates.
  • Amber “Check Hybrid” light illuminates for FMI 14.
  • Fault is stored in Hybrid Control Module (HCM) memory.
  • If this fault occurs while driving, the vehicle continues to operate and the transmission will shift to neutral once the vehicle stops.

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 7
    • Clutch Assembly
    • ECA
  • FMI 13, 14
    • Clutch Assembly
    • Cross-Shafts

Fault Code 2 – Motor/Generator Temperature Sensor Test

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