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:
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.
Warnings & Cautions
Danger: Danger indicates you will be severely injured or killed if do not follow the indicated procedure.
Warning: Warning indicates an immediate hazard, which could result in severe personal injury if you do not follow the indicated procedure.
Caution: Caution indicates vehicle or property damage could occur if you do not follow the indicated procedure.
Note: Note indicates additional detail that will aid in the diagnosis or repair of a component/system.
Follow the specified procedures in the indicated order to avoid personal injury:
1. If the high-voltage cones are around the vehicle and the lockout is installed on the PEC, the only person that should be allowed to start the vehicle is the person who signed the lockout tag.
2. Before working on a vehicle or leaving the cab while the engine is running, you should place the shift lever in “N” set the parking brake, and block the wheels.
3. For safety reasons, always engage the service brakes prior to selecting gear positions from “N.”
4. Before starting a vehicle always be seated in the driver’s seat, select “N” on the shift control, and set the parking brakes.
5. In vehicles with ePTO, the engine and/or
Motor/Generator can start in ePTO mode. Never perform any maintenance or work on vehicle, while in this mode.
6. 12-Volt Battery positive (+) and negative (-) must be disconnected prior to any welding on any Hybrid equipped vehicle.
Caution: Follow the specified procedures in the indicated order to avoid equipment malfunction or damage.
Caution: Do not release the parking brake or attempt to select a gear until the air pressure is at the correct level.
Caution: To avoid damage to the transmission during towing place the shift lever in “N” and lift the drive wheels off the ground or disconnect the driveline.
High-Voltage Warnings & Cautions
- Use CO2 or Dry Chemical Fire Extinguishers.
- The high-voltage wiring is covered in orange insulation or convoluted tubing and marked with warning labels at the connectors.
- All Eaton® Hybrid Diesel/Electric vehicles will be marked ‘Hybrid’ on the outside of the vehicle, along with the shift label on the dash.
- Refer to OEM for specific location of chassis mounted hybrid components.
- Do NOT cut into the orange high-voltage cables.
- Do NOT cut into or open the PEC.
- Do NOT cut into or open the DC/DC Converter.
- Do NOT cut into or open the Inverter.
A buffer zone must be set up and high-voltage insulated rubber gloves (class 0 with leather protectors) are required prior to working on high-voltage. Failure to follow these instructions may result in severe personal injury or death.
The rubber-insulated gloves that must be worn while working on the high-voltage system are class 0 with leather protectors. The rubber gloves should be tested before EVERY use following the rubber insulation gloves testing procedure found in “Diagnostic Tools/Service Publications” on page 6. Failure to follow these instructions may result in severe personal injury or death.
Before inspecting or working on any high-voltage cables or components the “High-Voltage Service Shutdown and Power-Up Procedure” on page 4 should be followed. Failure to follow these instructions may result in severe personal injury or death.
The Lockout and Tagout devices should only be removed by the technician that placed the Lockout and Tagout devices on the vehicle. Failure to follow these instructions may result in severe personal injury or death.
High-voltage rubber insulated gloves (class 0 with leather protectors) must be worn when working on any
high-voltage cables. The “High-Voltage Service Shutdown and Power-Up Procedure” on page 4 must be followed prior to removing any high-voltage cables. Failure to follow these instructions may result in severe personal injury or death.
High-voltage cables and wiring are orange and contain a warning label at the connectors. High-voltage components are marked with a label. High-voltage rubber insulated gloves (class 0 with leather protectors) must be used when working on any of these components. Failure to follow these instructions may result in severe personal injury or death.
High-Voltage Service Shutdown Procedures
1. Follow “High-Voltage Work Area” procedure.
2. Locate the red PEC Service Switch on the front of the PEC and push switch off.
3. Remove the Service Switch Cover and install the Lockout Bracket (J48506).
4. Fasten tag to the Lockout Bracket.
5. Ensure the PEC Service Switch can not move from the off position.
6. Allow the system to set for a minimum of 5 minutes to discharge high voltage.
7. Connect ServiceRanger and view the Data Monitor PID 116 called “High-Voltage Battery Potential.” Use SPN 520323 for J1939 connection “Battery Voltage RB” (Relay Box).
8. The voltage should be 30 volts or less. If the voltage is above 30 volts, do not work on the vehicle and contact Eaton® at 1-800-826-HELP (4357).
9. Turn ignition key off and proceed to repair or troubleshooting step.
Note: The voltage drops to zero when the key is off.
High-Voltage Service Power-Up Procedure
1. Install all high-voltage connectors into their locked positions.
2. If you are the person working on the vehicle, remove the Lockout Bracket and tag.
3. Reinstall the Lockout Bracket over the Service Switch.
4. Pull the Service Switch out and let vehicle set for 2 minutes.
5. Start vehicle when appropriate.
Eaton Hybrid Component and Connector Location

Eaton Hybrid Component and Connector Location MY09 Systems

STEP 1. Check for Active or Inactive fault codes.
- Key on with engine off.
- Connect ServiceRanger.
- Retrieve Snapshot and VPA data by creating a Service Activity Report within ServiceRanger.
- 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. - 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.
- 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.
- Set parking brakes and chock wheels.
- Place transmission in PD (Product Diagnositc) Mode.
- 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.
- Wiggle wiring and connections between 38-Way Transmission Harness Connector at the TECU and the black (X-Rail Motor) 2-Way Transmission Harness Connector.
- Wiggle wiring and connections between 38-Way Connector at the TECU and the blue (Y-Gear Motor) 2- Way Transmission Harness Connector.
- 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.
- 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.
- Key off.
- Disconnect 38-Way Transmission Harness Connector from the TECU.
- 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.
- Measure resistance between 38-Way Connector Pin 35 and Pin 37. Record reading.

- Measure the resistance between 38-Way Connector Pin 35 and ground.

- 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.
- 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.
- Reconnect 38-Way Transmission Harness to the TECU.
- Disconnect black 2-WayRail Motor Connector from the Transmission Harness.
- Remove connector cover of the 4-Way Diagnostic Connector.
- Measure resistance between the 2-Way Connector Body Pin A and the 4-Way Connector Pin C. Record reading(s).

- 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).

- 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.
- Key off.
- Disconnect blue 2-Way Rail Motor Connector from the Transmission Harness.
- 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.
- Measure resistance between the black 2-Way Connector Pin A and Pin B. Record reading(s).

- Measure resistance between the 2-Way Connector Pin A and ground. Record reading.

- 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.
- 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.
- Key off.
- Verify TECU battery power and ground supply from the OEM Vehicle Harness is connected properly and not corroded, damaged or loose.
- Disconnect 38-Way Vehicle Harness Connector at the TECU.
- 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.
- 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.

- 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.
- Key off.
- Disconnect 38-Way Transmission Harness Connector from the TECU.
- 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.
- Measure resistance between 38-Way Connector Pin 35 and Pin 37. Record reading(s).

- Measure resistance between 38-Way Connector Pin 35 and ground. Record readings.

- 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.
- Key off.
- Disconnect 38-Way Transmission Harness Connector from the Transmission Harness.
- 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.
- Measure resistance between 2-Way Connector Pin A and Pin B. Record reading(s).

- Measure resistance between 2-Way Connector Pin A and ground. Record readings.

- 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.
- Key off.
- Reconnect all connectors and the negative battery cable.
- Key on with engine off.
- Clear codes, see Clear Inactive Faults.
- Drive the vehicle and attempt to reset the code or duplicate issue.
- 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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