Eaton Fuller Hybrid Fault Code 6 – No HCM Operation

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. The Hybrid Control Module (HCM) is mounted to the transmission and it contains all of the software to control both the hybrid power electronics as well as the transmission operation.

Fault Code 6 – No HCM Operation 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.

Conditions to Set Fault Code Active

Conditions to Set Fault:

  • FMI 12 is set at key on if the HCM detects an internal failure.
  • FMI 14 is set when HCM can not complete writing to the Electrically Erasable Programmable Read-Only Memory  (EEPROM) during shut down.

Fallback When Fault Code 6 is set the following conditions occur:
• Amber “Check Hybrid” light illuminates.
• If the fault occurs at power up the vehicle may not crank.

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. 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 12, 14
    • HCM

Fault Code 6 – No HCM Operation Test

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