Fault Code 760: Rail C Operation
J1939: SA 3 SPN 6146 FMI 0, 1, 2, 7, 10, 14, 15, 16, 17, 18, 20, 21
Overview
The Mechatronic Transmission Module (MTM) is equipped with solenoids to direct pneumatic flow to actuate shift rails and sensors to monitor rail positions. The Transmission Control Module (TCM) compares the rail command and position to ensure proper rail operation. The solenoids, positions sensors and shift rails are located in the MTM and connected to the TCM at the 74-Way Transmission Harness Connector.
The TCM monitors the Rail C Operation. If a system failure is detected, the fault is set active.Detection
Conditions to Set Fault Code Active
FMI 0 – Data Valid But Above Normal (Most Severe): Rail C is unable to disengage the Primary Drive Gear, move aft, for 2 seconds. FMI 1 – Data Valid But Below Normal (Most Severe): Rail C is unable to disengage the Secondary Driven Gear, move fore, for 2 seconds. FMI 2 – Data Erratic: Rail C is unable to move the sliding clutch to neutral during a rail calibration. FMI 7 – Mechanical System Not Responding: Rail C is unable move from neutral toward the Primary Drive Gear for 2 seconds. FMI 10 – Abnormal Rate of Change: Rail C is unable to confirm low rail speed velocity during a rail calibration. FMI 14 – Special Instructions: Rail C is unable to move from neutral toward the Secondary Driven Gear for 2 seconds. FMI 15 – Data Valid but Above Normal (Least Severe): Rail C is unable to fully engage the Primary Drive Gear for 2 seconds. FMI 16 - Data Valid but Above Normal (Moderately Severe): Rail C is unable to achieve neutral from the Primary Drive Gear for 2 seconds. FMI 17 – Data Valid but Below Normal (Least Severe): Rail C is unable to fully engage the Secondary Driven Gear for 2 seconds. FMI 18 – Data Valid but Below Normal (Moderately Severe): Rail C is unable to achieve neutral from the Secondary Driven Gear for 2 seconds. FMI 20 – Data Drifted High: Rail C travel was greater than expected during a rail calibration. FMI 21 – Data Drifted Low: Rail C travel was less than expected during a rail calibration.
FMI 0, 1: FMI 2, 10, 20, 21: FMI 7, 15: FMI 14, 17: FMI 16, 18:Fallback
Conditions to Set Fault Code Inactive
FMI 0, 1, 7, 14, 16, 18: Condition no longer exists FMI 2, 10, 20, 21: Successful rail calibration FMI 15, 17: Key cycle
Possible Causes
All FMIs:
Additional Tools
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 PortComponent Identification
Fault Code 760 Troubleshooting
A Purpose:Check for active or inactive fault codes. Set vehicle parking brake and chock wheels. Record the transmission fault codes, FMIs, occurrences, and timestamps from the Service Activity Report created during the Diagnostic Procedure. If Fault Code 760 FMI 0, 1, 2, 18 is Active or Inactive, Go to Step E If Fault Code 760 FMI 7, 10, 14, 16, 20, 21 is Active or Inactive, Go to Step B If Fault Code 760 FMI 15, 17 is Active or Inactive, go to TAIB-1004 Fault Code 760 Rail C Operation or 775 Rail D Operation FMI 15/17 - Endurant HD. B Purpose:Verify condition of the vehicle air system supply line and MTM air inlet port. Key off. Refer to OEM guidelines and vent the vehicle air supply line to the MTM. Refer to OEM guidelines and remove the vehicle air supply line at the MTM. Inspect the vehicle air supply line and the MTM air inlet port for contamination, moisture, corrosion and/or debris. Note: Verify the MTM inlet screen is installed and free of contamination and/or debris. If contamination is found, refer to OEM guidelines for repair or replacement of the vehicle air system. Replace the Mechatronic Transmission Module (MTM) and reference the Lower Countershaft Cover and Inertia Brake Service Procedure for replacement of the Inertia Brake Assembly. Go to Step V Note: MTM removal and installation requires the transmission to be removed from the vehicle. Reference Endurant HD Service Manual TRSM0950, Transmission Removal Service Procedure. If no contamination is found, Go to Step C C Purpose:Verify mechanical condition of the Primary Drive Gear and Secondary Driven Gear. Remove the MTM. Note: MTM removal and installation requires the transmission to be removed from the vehicle. Reference Endurant HD Service Manual TRSM0950, Transmission Removal Service Procedure. Inspect the Primary Drive Gear for excessive fore and aft movement. Inspect the Secondary Driven Gear for excessive fore and aft movement. If excessive gear movement is evident, inspect for cause of excessive gear movement and repair. Go to Step V If no excessive gear movement is evident, Go to Step D D Purpose:Verify mechanical condition of the Rail C Sliding Clutch and clutching teeth. Inspect the Rail C Sliding Clutch yoke slot for wear. Shift the Rail C Sliding Clutch to the neutral position (if necessary). Shift the Rail C Sliding Clutch into the Primary Drive Gear engagement position (fore). Inspect the Rail C Sliding Clutch clutching teeth for wear. Return the Rail C Sliding Clutch to neutral. Shift the Rail C Sliding Clutch into the Secondary Driven Gear engagement position (aft). Inspect the Rail C Sliding Clutch clutching teeth for wear. Return the Rail C Sliding Clutch to neutral. If the Rail C Sliding Clutch shifts into all three positions and no clutching teeth wear is present, replace Mechatronic Transmission Module (MTM). Go to Step V If the Rail C Sliding Clutch does not shift into all three positions or clutching teeth wear is present, refer to the Primary Drive Gear Replacement procedure for replacement of the Primary Drive Gear. Replace the Rail C Sliding Clutch, Secondary Driven Gear and Mechatronic Transmission Module (MTM). Go to Step V E Purpose:Verify MTM Serial Number. Record MTM Serial Number (Item 2). If MTM Serial Number is less then 12S22342093445, go to Endurant HD Service Manual TRSM0950 Appendix MTM Rail B, C and D Cylinder Inspection Procedure. If MTM Serial Number is equal to or greater than 12S22342093445, Go to Step B V Purpose:Verify repair. Key off. Reconnect all connectors and verify that all components are properly installed. Key on with engine off. Connect ServiceRanger. Go to “Fault Codes”. Select “Clear All Faults”. Operate vehicle and attempt to reset the fault code or duplicate the previous complaint. Check for fault codes using ServiceRanger. If no fault codes set and the vehicle operates properly, test complete. If Fault Code 760 sets Active during operation, Go to Step A If a fault code other than 760 sets Active, troubleshoot per the Fault Code Isolation Procedure Index.
