Eaton Fuller Hybrid Transmission Fault Code 68 – Grade Sensor Fault

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 Grade Sensor is an internal component of the Hybrid Control Module (HCM). It calculates the vehicle grade needed for the Hill Start Assist (HSA) feature to function properly. HSA momentarily holds the Service Brakes at launch to allow single-foot pedal operation without the vehicle rolling back.

Fault Code 68 – Grade Sensor Fault Detection

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

  • Hybrid Control Module (HCM) ignition voltage is greater than 7 volts and less than 16 volts.

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

Conditions to Set Fault Code Active

  • FMI 12 is set when the grade sensor is not Active or present and HSA is enabled in the HCM configuration.
  • FMI 13 is set when HSA is enabled in the HCM configuration but the grade sensor has not been calibrated.
  • FMI 14 is set when the HCM is equipped with a Grade Sensor, HSA is enabled and the signal from the sensor is out of range.

Fallback When Fault Code 68 is set the following conditions occur:

  • Amber “Check Hybrid” light illuminates.
  • Fault is stored in Hybrid Control Module (HCM) memory.

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

  • FMI 12
    • Incorrect HCM configuration
    • HCM
  • FMI 13
    • Grade Sensor calibration
    • Incorrect HCM configuration
  • FMI 14
    • HCM
    • Incorrect HCM mounting to transmission

Fault Code 68 – Grade Sensor Fault Test

Component Identification:

Hybrid Control Module for Eaton Fuller transmission

1. Hybrid Control Module (HCM)
2. Nut (3)
3. 38-Way System Connector Plug-in
4. 38-Way Vehicle Connector Plug-in
5. Mounting Plate

NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations.

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