Endurant XD
TRTS0960 EN-US
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September 2024 - A

Fault Code 780: Rail E Operation

J1939: SA 3 SPN 6148 FMI 0, 1, 2, 7, 10, 14, 15, 16, 17, 18, 20, 21

Overview

The Endurant XD Series transmissions are equipped with five Shift Rails: A, B, C, D, and E. The shift rails are mounted in shift rail cylinders in the Mechatronic Transmission Module (MTM). Solenoid valves direct vehicle Supply Air to and from the shift rail cylinders for shift rail actuation. Position sensors monitor shift rail positions and speed sensors monitor shaft speeds.

The sensor information is provided to the Transmission Control Module (TCM) for the purpose of making shift decisions, confirming gear engagement, and monitoring shift rail positions. The TCM compares the shift rail commands to the shift rail positions and shaft speeds (ratio calculation) to ensure the transmission is operating properly.

The sensors and shift rails are located in the MTM and connected to the TCM at the 74-Way Transmission Harness Connector.

Detection

The TCM monitors Shift Rail D operation. If a system failure is detected, the fault is set Active.

Conditions to Set Fault Code Active

FMI 0 – Data Valid But Above Normal (Most Severe): Rail E unable to disengage High Range, move aft, for 2 seconds.

FMI 1 – Data Valid But Below Normal (Most Severe): Rail E unable to disengage Low Range, move fore, for 2 seconds.

FMI 2 – Data Erratic: During a rail calibration, Rail E unable to move to neutral position.

FMI 7 – Mechanical System Not Responding: Rail E unable move from neutral position toward High Range for 2 seconds.

FMI 10 – Abnormal Rate of Change: During a rail calibration, Rail E Position Sensor unable to confirm low rail velocity.

FMI 14 – Special Instructions: Rail E unable to move from neutral position toward Low Range for 2 seconds.

FMI 15 – Data Valid but Above Normal (Least Severe): Rail E unable to engage High Range for 2 seconds.

FMI 16 - Data Valid but Above Normal (Moderately Severe): Rail E unable to move from High Range to neutral position for 2 seconds.

FMI 17 – Data Valid but Below Normal (Least Severe): Rail E unable to engage Range Low for 2 seconds.

FMI 18 – Data Valid but Below Normal (Moderately Severe): Rail E unable to move from Low Range to neutral position for 2 seconds.

FMI 20 – Data Drifted High: During a rail calibration, Rail E travel was greater than expected.

FMI 21 – Data Drifted Low: During a rail calibration, Rail E travel was less than expected.

Fallback

FMI 0, 14, 16, 17:

  • Amber warning lamp on
  • Low Range engagement prohibited
  • Transmission may launch in High Range

FMI 1:

  • Amber warning lamp on
  • High Range engagement prohibited

FMI 2:

If Rail C and D positions are known and Rail C or D are either fully engaged or fully disengaged:

  • Amber warning lamp on
  • Shift Rail C movement prohibited
  • Shift Rail D movement prohibited

If Rail C and D positions are not known and Rail C or D are not fully engaged or fully disengaged:

  • Shift Rail C movement prohibited
  • Shift Rail D movement prohibited
  • Inertia Brake activation prohibited
  • PTO Mode prohibited
  • If vehicle is moving:
    • Red stop lamp on

FMI 10, 20, 21:

If Rail E position is known and Rail E is fully engaged in either High or Low Range:

  • Amber warning lamp on
  • Shift Rail E movement prohibited

If Rail E position is not known and Rail E is not fully engaged in High or Low Range:

  • Shift Rail E movement prohibited
  • Urge to Move and Creep Mode prohibited
  • Non-Neutral modes prohibited
  • PTO Mode prohibited
  • If vehicle is moving
    • Red stop lamp on

FMI 7, 15, 18:

  • Amber warning lamp on
  • High Range engagement prohibited
  • If vehicle is moving and no start gear available
    • Red stop lamp on

Conditions to Set Fault Code Inactive

FMI 7, 14, 16, 18: Fault condition no longer exists for 1 second.

FMI 0, 1, 2, 10, 15, 17, 20, 21: Key cycle and fault condition no longer exists.

Possible Causes

All FMIs:

  • Vehicle Air System
    • Contamination
  • MTM
    • Rail E Fore Solenoid – internal failure
    • Rail E Aft Solenoid – internal failure
    • Rail E Shift Cylinder – stuck piston or damaged seals
    • Rail E Position Sensor – in range internal failure
    • Rail E Shift Rail – broken, detached
    • Rail E Shift Yoke – broken, detached
  • Rear Housing
    • Rail E Detent – binding
    • Rail E Shift Rail – binding
    • Rail E Bushing – worn
    • Rail E Synchronizer

Additional Tools

  • Endurant XD Service Manual TRSM0960
  • MTM Alignment Tool (RR1086TR-1)

Component Identification

_Graphics/LineArt/TRTS0960_FC215_ComponentID.png

1. Transmission Control Module (TCM) Cover

2. Transmission Control Module (TCM)

3. 74-Way Transmission Harness Connector (TCM-side)

4. 74-Way Transmission Harness Connector (MTM-side)

5. Transmission Control Module (TCM) Seal

6. MTM Air Inlet Port

Fault Code 780 Troubleshooting

A
Purpose:Check for active or inactive fault codes.

  1. Set vehicle parking brake and chock wheels.

  2. Record transmission fault codes, FMIs, occurrences, and timestamps from Service Activity Report created during the Diagnostic Procedure.

  • If Fault Code 780 FMI 0, 1, 2, 7, 10, 14, 15, 16, 17, 18, 21 is Active or Inactive, Go to Step B

  • If Fault Code 780 FMI 20 is Active or Inactive, Contact Eaton Cummins Automated Transmission Technologies for further diagnostic instructions. For Help Line phone numbers, go to Contact Information, Go to Step V

B
Purpose:Verify condition of vehicle air system supply line and MTM air inlet port.

  1. Key off.

  2. Refer to OEM guidelines and vent vehicle air supply line to MTM.

  3. Refer to OEM guidelines and remove vehicle air supply line at MTM.

  4. Inspect vehicle air supply line and MTM air inlet port for contamination, moisture, corrosion and/or debris.

    Note: Verify MTM inlet screen is installed and free of contamination and/or debris.

    _Graphics/LineArt/TRTS0950_FC511_MTMAirInletPort.png

  • If contamination is found, refer to OEM guidelines for repair or replacement of vehicle air system. Replace Mechatronic Transmission Module (MTM) and Inertia Brake Assembly. Go to Step V

    Note: MTM removal and installation requires transmission be removed from vehicle. Reference Endurant XD Service Manual TRSM0960, Transmission Removal Service Procedure.

  • If no contamination is found, Go to Step C

C
Purpose:Verify mechanical movement of Rail E Synchronizer.

  1. Remove MTM.

    Note: MTM removal and installation requires transmission be removed from vehicle. Reference Endurant XD Service Manual TRSM0960, Transmission Removal Service Procedures.

  2. Install MTM Alignment Tool (RR1086TR-1) onto main housing.

    Note: Reference Appendix/Manually Actuate Rail E Procedure.

  3. Using Rail E Lever, shift Rail E into neutral position (if necessary).

  4. Shift Rail E into High Range engagement position (fore).

  5. Return Rail E to neutral position.

  6. Shift Rail E into Low Range engagement position (aft).

  7. Return Rail E to neutral position.

D
Purpose:Verify mechanical movement of Rail E Range Synchronizer without detent.

  1. Remove the Rail E Detent Plug, Spring and Detent.

  2. Install MTM Alignment Tool (RR1086TR-1) onto main housing.

  3. Using Rail E Lever, shift Rail E into neutral position (if necessary).

  4. Shift Rail E into High Range engagement position (fore).

  5. Return Rail E to neutral position.

  6. Shift Rail E into Low Range engagement position (aft).

  7. Return Rail E to neutral position.

  • If Rail E Detent could not be removed, Go to Step E

  • If Rail E shifts into all three positions, replace Rail E Detent Plug, Spring, Detent and Rear Housing. Go to Step V

  • If Rail E does not into all three positions, Go to Step E

E
Purpose: Verify mechanical condition of Rail E Synchronizer and Shift Rail E.

  1. Remove Rear Housing.

  2. Inspect Rail E Synchronizer, Shift Rail, Detent and Rear Housing Detent bore.

  • Contact Eaton Cummins Automated Transmission Technologies at +1 800-826-4357 for further diagnostic instructions. Go to Step V

V
Purpose:Verify repair.

  1. Key off.

  2. Reconnect all connectors and verify all components are properly installed.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Go To “Fault Codes”.

  6. Select “Clear All Faults”.

  7. Operate vehicle and attempt to reset the fault code or duplicate the previous complaint.

  8. Check for fault codes using ServiceRanger.