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

STEP 1. Check for Active or Inactive fault codes.

  1. Key on with engine off.
  2. Connect ServiceRanger.
  3. Retrieve Snapshot and VPA data by creating a Service Activity Report within ServiceRanger.
  4. Update transmission software to latest available level.
    Caution: To avoid damaging the TECU, use an Eaton-approved communications adapter and ensure all satellite systems are disabled before updating software.
  5. Retrieve and record the transmission fault codes and FMIs, and their occurrences and timestamps.
    • If either Fault Code 33 or 34 are Active, troubleshoot it first per Fault Code Isolation Procedure.
    • If Fault Code 61 is Active and Fault Code 33 or Fault Code 34 are Inactive or not set, go to Step 4.
    • If Fault Code 61 is Inactive and Fault Code 33 or Fault Code 34 are Inactive or not set, go to Step 2.

STEP 2. Verify condition of power and ground supply.

  1. Perform the Electrical Pretest Gen1 ECA. Record the reading(s) from the Load Test in Step 3 of the Electrical Pretest.
    • If the Electrical Pretest fails, repair per Electrical Pretest instructions. Retest vehicle operation.
    • If the Electrical Pretest passes, go to Step 3.

STEP 3. Use Product Diagnostic (PD) Mode to locate intermittent failures.

  1.  Set parking brakes and chock wheels.
  2. Place transmission in PD (Product Diagnositc) Mode.
  3. Wiggle wiring and connections between the 38- Way OEM Vehicle Harness Connector at the TECU and vehicle battery supply. Look for signs of rubbing or chafing.
  4. Wiggle wiring and connections between 38-Way Transmission Harness Connector at the TECU and the black (X-Rail Motor) 2-Way Transmission Harness Connector.
  5. Wiggle wiring and connections between 38-Way Connector at the TECU and the blue (Y-Gear Motor) 2- Way Transmission Harness Connector.
  6. Exit PD Mode by powering down.
    Important: Allow 2–3 minutes for the TECU to perform a complete power-down sequence before proceeding.

    • If any faults set Active while wiggling the Vehicle Harness, refer to OEM guidelines for repair or replacement of the OEM wiring. Go to Step 13.
    • If any fault sets Active while wiggling the Transmission Harness, replace the Transmission Harness. Go to Step 13.
    • If no faults set Active while wiggling either harness, go to Step 4.

STEP 4. Verify which FMI set.

  1.  Determine which FMI set for Fault Code 61.
    • If FMI 1 or 12 set, go to Step 5.
    • If FMI 5 set and is Active, go to Step 5.
    • If FMI 5 set and is Inactive, go to Step 11.
    • If FMI 6 set, replace TECU. Go to Step 13.

STEP 5. Verify proper resistance through the Transmission Harness and Rail Motor.

  1. Key off.
  2. Disconnect 38-Way Transmission Harness Connector from the TECU.
  3. Verify that the 38-Way Connector is free from corrosion; terminals are not bent, spread, or loose terminals; and there is no damage to the connector body.
  4. Measure resistance between 38-Way Connector Pin 35 and Pin 37. Record reading.
    Measure resistance between 38-Way Connector Pin 35 and Pin 37. Record reading.
  5. Measure the resistance between 38-Way Connector Pin 35 and ground. 38-way connector pin 35
  6. Compare reading(s) to specified range:
    • If reading(s) is in range, go to Step 6.
    • If reading(s) is out of range, go to Step 8.

STEP 6. Verify which FMI set.

  1. Determine which FMI set for Fault Code 61.
    • If FMI 1 set, replace X-Y Shifter and Transmission Harness. Go to Step 13.
    • If FMI 5 set, go to Step 7.
    • If FMI 12 set, go to Step 8.

STEP 7. Verify internal circuit resistance of the TECU.

  1. Reconnect 38-Way Transmission Harness to the TECU.
  2. Disconnect black 2-WayRail Motor Connector from the Transmission Harness.
  3. Remove connector cover of the 4-Way Diagnostic Connector.
  4. Measure resistance between the 2-Way Connector Body Pin A and the 4-Way Connector Pin C. Record reading(s).2-Way Connector Body
  5. Reverse meter leads and take the same measurement between the 2-Way Connector Pin A and the 4-Way Connector Pin C. Record reading(s).Fuller 4-Way Connector Pin C
  6. Compare reading(s) to specified range in recordings.
    • If both readings are in range, replace the X-Y Shifter. Go to Step 13.
    • If either readings is out of range, replace the TECU. Go to Step 13.

STEP 8. Verify the resistance of the X-Y Rail Motor and verify motor is not shorted to ground.

  1. Key off.
  2. Disconnect blue 2-Way Rail Motor Connector from the Transmission Harness.
  3. Verify 2-Way Connector is free from any corrosion; the terminals are not bent, spread or loose, and there is no damage to the connector body.
  4.  Measure resistance between the black 2-Way Connector Pin A and Pin B. Record reading(s). 2-Way Rail Motor Connector Pin A and Pin B
  5. Measure resistance between the 2-Way Connector Pin A and ground. Record reading.Eaton Fuller Transmission Rail Motor Circuit 2-Way Connector Pin A
  6. Compare reading(s).
    • If reading(s) is in range, go to Step 9.
    • If reading(s) is out of range, replace the X-Y Shifter. Go to Step 13.

STEP 9. Verify which FMI set.

  1. Determine which FMI set for Fault Code 61.
    • If FMI 1 set, replace Transmission Harness. Go to Step 13.
    • If FMI 5 set, replace Transmission Harness. Go to Step 13.
    • If FMI 12 set, go to Step 10.

STEP 10. Load Test the vehicle power supply to the TECU.

  1. Key off.
  2. Verify TECU battery power and ground supply from the OEM Vehicle Harness is connected properly and not corroded, damaged or loose.
  3. Disconnect 38-Way Vehicle Harness Connector at the TECU.
  4. Verify that the 38-Way Connector is free from corrosion; terminals are no bent, spread, or loose; and there is no damage to the connector body.
  5. Load test the vehicle Power Supply Harness with an external load source. Use a sealed beam headlamp or blower motor attached to Pin 35 (power) and Pin 37 (ground). Load test for 5 minutes to verify the harness will carry a load with the 30-amp fuse installed.Eaton Fuller Transmission Power Supply Harness
  6. Wiggle the harness during the Load Test from the vehicle batteries to the TECU.
    • If issues are found with the Vehicle Harness or connectors, refer to OEM guidelines for repair or replacement of OEM wiring and continue Load Test.
    • If the Vehicle Harness does not carry a load, refer to OEM guidelines for repair or replacement of OEM wiring. Go to Step 13.
    • If no issues are found with the Vehicle Harness or connectors and the power supply carries a load, replace the TECU. Go to Step 13.

STEP 11. Verify proper resistance through the Transmission Harness and Rail Motor.

  1. Key off.
  2. Disconnect 38-Way Transmission Harness Connector from the TECU.
  3. Verify that the 38-Way Connector is free from corrosion, terminals are not bent, spread, or loose; and there is no damage to the connector body.
  4.  Measure resistance between 38-Way Connector Pin 35 and Pin 37. Record reading(s).Fuller Transmission Harness and Rail Motor resistance test
  5. Measure resistance between 38-Way Connector Pin 35 and ground. Record readings. proper resistance through the Transmission Harness and Rail Motor test for Eaton Fuller transmissions
  6. Compare recorded reading(s).
    • If reading(s) is in range, replace the X-Y Shifter. Go to Step 13.
    • If reading(s) is out of range, go to Step 12.

STEP 12.Verify the internal resistance of the X-Y Shifter Rail Motor and verify motor is not shorted to ground.

  1. Key off.
  2. Disconnect 38-Way Transmission Harness Connector from the Transmission Harness.
  3. Verify that the 2-Way Connector is free from corrosion, terminals are not bent, spread, or loose; and there is no damage to the connector body.
  4.  Measure resistance between 2-Way Connector Pin A and Pin B. Record reading(s).Shifter Rail Motor and verify motor is not shorted to ground test
  5. Measure resistance between 2-Way Connector Pin A and ground. Record readings. Eaton Fuller Transmission Rail Motor Circuit 2-Way Connector Pin A
  6. Compare recorded reading(s).
    • If reading(s) is in range, replace the Transmission Harness. Go to Step 13.
    • If reading(s) is out of range, replace the X-Y Shifter. Go to Step 13.

STEP 3. Verify repair.

  1. Key off.
  2. Reconnect all connectors and the negative battery cable.
  3.  Key on with engine off.
  4. Clear codes, see  Clear Inactive Faults.
  5. Drive the vehicle and attempt to reset the code or duplicate issue.
  6. Check for codes, see View Active and Inactive Faults.
    • If no codes, test is complete.
    • If fault Code 61 appears, find error in testing, go to Step 1.
    • If a code other than 61 appears, see Fault Code Index List.

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