Eaton Fuller Hybrid Transmission Fault Code 61: Rail Motor Circuit Fault

Fault code for Eaton Hybrid Drive Systems models (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 Transmission is equipped with an X-Y Shifter that selects a transmission gear. The X-Y Shifter motors are controlled with electrical current supplied by the TECU to move the Shift Finger either side-to-side (rail selection) or fore-and-aft (gear engagement and disengagement). Fault Code 61 indicates a failure with the circuit  controlling the Rail Motor and the side-to-side movement of the X-Y Shift Finger. 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 DC/DC Converter is connected to the Power Electronics Carrier (PEC), which provides 340 volts DC. The voltage is reduced to 12-volts DC and maintains the 12-volt system during engine off PTO operation. The DC/DC maintains a steady 14.2 (±0.2) (MY08 Systems) or 12.6 (MY09 System) volts output and increases the amperage with vehicle demand up to 1.5 kw or 120 amps.

Fault Code 61: Rail Motor Circuit Fault Detection

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

The system can identify an issue with the X-Y Shifter Rail Motor circuit, the TECU rail motor controller or the power and ground connections to the TECU under the following conditions:

  • FMI 1 and 12 can be detected when the X-Y Rail Motor is energized
  • FMI 5 and 6 can be detected when the X-Y Rail Motor is not energized

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

Conditions to Set Fault Code Active

  • FMI 1 – Data Valid but Below Normal: Transmission fails to complete a shift and the measured current draw of the Rail Motor is below expected values.
  • FMI 5 – Current Below Normal or Open Circuit: TECU detects an open circuit or a short-to-ground condition on the Rail Motor circuit for 0.5 second at power up or prior to a shift.
  • FMI 6 – Current Above Normal or Shorted Circuit: TECU detects a short-to-power on the Rail Motor circuit for 0.5 seconds at power up or prior to a shift.
  • FMI 12 – Bad Intelligent Device: Transmission fails to complete a shift and the TECU detects intermittent fluctuations in supply voltage due to poor  connections, shorted Rail Motor circuit or a hardware failure of the TECU.

Fallback When Fault Code 61 is set the following conditions occur:

  • “F” flashes in the gear display.
  • Service light flashes (if equipped).
  • Engine may not crank.
  • Transmission may not engage a gear from neutral.
  • Transmission does not shift while the vehicle is moving.
  • Until the fault becomes Inactive, driver may have to shut off engine with transmission in gear.

Conditions to Set Fault Code Inactive

FMI 1, 12: This fault is set Inactive when the shift is completed.
FMI 5, 6: This fault is set Inactive when the open or short circuit condition is not detected for 0.5 seconds.

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

  • FMI 1, 5
    • Transmission Harness
    – Terminals bent, spread, corroded or loose
    – Wiring shorted to ground, shorted to power or open
    •X-Y Shifter Rail Motor
    – Terminals bent, spread, corroded or loose
    – Rail Motor shorted to ground, partial short to ground, shorted to power or open
    – Rail Motor internal failure
    •TECU
    – Internal failure
  • FMI 6
    • Transmission Harness
    – Wiring shorted to power
    •TECU
    – Internal failure
  • FMI 12
    • OEM Power Supply
    – Poor power or ground supply to TECU (may be in conjunction with Fault Codes 33 or 34)
    – Battery failure
    – Terminals bent, spread, corroded or loose
    – Wiring shorted to ground, shorted to power or open
    •OEM Batteries
    – Internal failure
    •OEM 30-amp Battery Fuse
    – Terminals bent, spread, corroded or loose
    – Fuse missing or improperly seated
    •TECU
    – Internal failure

Fault Code 61: Rail Motor Circuit Fault Test

Component Identification:

Rail Motor Circuit Fault

1. X-Y Shifter
2. 2-Way Rail Motor Connector (black)
3. 2-Way Rail Motor Connector Body (black)
4. 4-Way Diagnostic Connector
5. 38-Way Transmission Harness Connector
6. 38-Way Vehicle Harness Connector
7. Transmission Electronic Control Unit (TECU)

NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY09 Systems.

TECU rail motor connector locations

1. Transmission Electronic Control Unit (TECU)
2. 38-Way Transmission Harness Connector
3. 2-Way Rail Motor Connector Body (black)
4. 2-Way Rail Motor Connector (black)
5. 4-Way Diagnostic Connector

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