Eaton Fuller Hybrid Transmission Fault Code 61 – Rail Select Motor

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, the Electric Shifter contains two electric motors—the Rail motor and Gear motor. These motors move a shift finger between the various rails which engage the shift rails. Power is supplied from the Transmission Electronic Control Unit (TECU). 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 Select Motor Detection

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

  • TECU ignition voltage is greater than 7 volts and less than 16 volts.
  • TECU System Battery Voltage Low Fault is Inactive.
  • TECU System Battery Voltage Weak Fault is Inactive.
  • Electric Shifter is not energized and the shift finger is not moving.

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

Conditions to Set Fault Code Active

  • FMI 5 and 6 are set when the TECU detects 5 continuous open or short conditions on the Electric Shifter while the motor drive circuit is idle in a 500 ms interval.

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

  • Red “Service” light illuminates and an “F” flashes in the gear display.
  • Fault is stored in TECU memory.
  • The operation mode changes to “AutoShift Fallback” mode.
  • If this fault occurs while moving, the transmission remains in the current gear and the clutch opens when 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 5, 6
    • Electric Shifter
    • TECU
    • Transmission Harness

Fault Code 61 – Rail Select Motor Test

Component Identification:

Harness Front View TECU - Vehicle Interface Connector

Harness Front View
(TECU – System Interface Connector)

Eaton Fuller transmission rail select motor

Harness Front View
(Rail Select Motor

NOTE: Refer to the Eaton Hybrid Component and Connector Location for Connector Locations in MY08 Systems

TECU Rail Select Motor Connector location on Eaton Fuller transmission

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