Fault Code 320: Rail E Position
J1939: SA 3 SPN 5942 FMI 0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 16, 18, 20, 21
Overview
The Endurant HD transmission is equipped with position sensors to monitor shift rails B, C, D and E. The position sensors detect the rail position through the proximity of a magnet mounted to each shift rail. Shift Rail E actuates the Rail E synchronizer to engage High or Low Range. The position sensors are located in the Mechatronic Transmission Module (MTM) and connected to the Transmission Control Module (TCM) at the 74-Way Transmission Harness Connector.
Detection
The TCM monitors the Rail E Position. If a system failure is detected, the TCM sets the fault code Active.
Conditions to Set Fault Code Active
FMI 0 – Data Valid But Above Normal – Most Severe: Rail E Position Sensor indicated Rail E moved beyond the calibrated High Range engagement position for 1 second.
FMI 1 – Data Valid But Below Normal – Most Severe: Rail E Position Sensor indicated Rail E moved beyond the calibrated Low Range engagement position for 1 second.
FMI 2 – Data Erratic: Rail E Position Sensor out of normal operating duty cycle (5% to 95%) for 1 second.
FMI 3 – Voltage Above Normal or Shorted High: Rail E Position Sensor shorted to power for 1 second.
FMI 4 – Voltage Below Normal or Shorted Low: Rail E Position Sensor shorted to ground for 1 second.
FMI 5 – Current Below Normal or Open Circuit: Rail E Position Sensor open circuit for 1 second.
FMI 6 – Current Above Normal or Grounded Circuit: Rail E Position Sensor out of normal operating voltage (4.75V to 5.25V) for 1 second.
FMI 8 – Abnormal Frequency: Rail E Position Sensor out of normal operating frequency for 1 second.
FMI 9 – Abnormal Update Rate: Rail E Position Sensor could not detect magnet for 1 second.
FMI 10 – Abnormal Rate Of Change: Rail E Position Sensor reporting rate of change exceeded when no movement commanded for 1 second.
FMI 12 – Bad Intelligent Device: Rail E Position Sensor internal self-check out of range for 1 second.
FMI 16 - Data Valid but Above Normal (Moderately Severe): Rail E Position Sensor reporting uncommanded movement toward neutral from High Range engagement position while speed sensors report a valid High Range ratio.
FMI 18 – Data Valid but Below Normal (Moderately Severe): Rail E Position Sensor reporting uncommanded movement toward neutral from Low Range engagement position while speed sensors report a valid Low Range ratio.
FMI 20 – Data Drifted High: Rail E Position Sensor reporting High Range disengagement while speed sensors report a valid High Range ratio for 1 second.
FMI 21 – Data Drifted Low: Rail E Position Sensor reporting Low Range disengagement while speed sensors report a valid Low Range ratio for 1 second.
Fallback
FMI 0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 16, 18, 20, 21
- If Rail E position is known and fully engaged:
- Amber warning lamp on
- Shift Rail E movement prohibited
- If Rail E position is not known or not fully engaged:
- Amber warning lamp on
- Shift Rail E movement prohibited
- Non-Neutral Modes prohibited
- PTO mode prohibited
- If vehicle is moving – Red stop lamp on
Conditions to Set Fault Code Inactive
FMI 2, 3, 4, 5, 6, 8, 9: Rail E Position Sensor in range for 10 seconds.
FMI 0, 1, 10, 16, 18, 20, 21: Key cycle and condition no longer exists.
FMI 12: Rail E Position Sensor internal self-checks in range for 10 seconds.
Possible Causes
FMI 0, 1:
- MTM
- Rail E Yoke
- Internal Transmission
- Rail E Synchronizer
FMI 2, 3, 4, 5, 6:
- MTM - Rail E Position Sensor
- Damaged
- Internal failure
- MTM - Transmission Harness
- Wiring shorted to power, shorted to ground or open.
- TCM
- Software issue
- Internal failure
FMI 8:
- MTM - Rail E Position Sensor
- Damaged
- Internal failure
- MTM - Transmission Harness
- Wiring shorted to power, shorted to ground or open.
- TCM
- Incorrect MTM Type configured
- Software issue
- Internal failure
FMI 9:
- MTM Installation
- Rail E notch facing down
- MTM - Rail E Cylinder
- Magnet loose
- Magnet detached
- MTM - Rail E Position Sensor
- Loose
- Damaged
FMI 12:
- TCM
- Software issue
- Internal failure
FMI 10, 20, 21:
- MTM - Rail E Position Sensor
- Internal failure
FMI 16, 18:
- MTM - Rail E Position Sensor
- Internal failure
- Internal transmission
- Rail E Detent
- Rail E Shift Rail
- Rail E Synchronizer
Additional Tools
- Endurant HD Service Manual TRSM0950
- Eaton Breakout Box with 74-Way Eaton Diagnostic Adapter - RR1029TR
- Digital Volt/Ohm Meter (DVOM)
Component Identification
 |
1. Transmission Control Module (TCM) Cover 2. Transmission Control Module (TCM) 3. 74-Way Transmission Harness Connector (MTM-side) 4. 74-Way Transmission Harness Connector (TCM-side) 5. Transmission Control Module (TCM) Seal 6. Mechatronic Transmission Module (MTM) |
Fault Code 320 Troubleshooting
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 320 FMI 9 is Active and MTM was recently replaced, Go to Step I
If Fault Code 320 FMI 9 is Active or Inactive and MTM was not recently replaced, Go to Step B
If Fault Code 320 FMI 0, 1 is Active or Inactive, Go to Step F
If Fault Code 320 FMI 2, 3, 4, 5, 6, 10, 18, 20, 21 is Active or Inactive, Go to Step B
If Fault Code 320 FMI 8 and all the following fault codes are Active:
- Fault Code 200 FMI 14
- Fault Code 275 FMI 5
- Fault Code 295 FMI 8
- Fault Code 315 FMI 8
Note: Fault Code 596 FMI 5 may also be Active depending on MTM Type configured in TCM.
Go to Configure Mechatronic Transmission Module (MTM) Type. Go to Step V
If Fault Code 320 FMI 8 is Active or Inactive, Go to Step B
If Fault Code 320 FMI 12 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
If Fault Code 320 FMI 16 is Active or Inactive, create a Service Activity Report and select “Send to Eaton”. Go to Step D
Key off.
Remove the TCM from the MTM with the 20-Way TCM Vehicle Harness Connector and 20-Way TCM Body Harness Connector connected.
Inspect the TCM side of the 74-Way Transmission Harness Connector, verify the connector is free from contamination and corrosion; the terminals are not bent, spread or loose; and there is no damage to the connector body.
Inspect the TCM Seal, verify the seal is properly installed and not damaged.
If contamination or damage is found to the TCM side of the 74-Way Transmission Harness Connector, replace the Transmission Control Module (TCM) and Mechatronic Transmission Module (MTM). 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 or damage is found, Go to Step C
Key off.
Connect the Eaton Breakout Box with 74-Way Eaton Diagnostic Adapter to the TCM side of the 74-Way Transmission Harness Connector.
Measure resistance at the Eaton Breakout Box between Pin 73 and Pin 74. Record reading in table.
Key on.
Measure voltage at the Eaton Breakout Box between Pin 72 and Pin 74. Record reading in table.
Compare reading(s) in table.
If readings are in range, replace the Mechatronic Transmission Module (MTM). 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 readings are out of range, replace Transmission Control Module (TCM). Go to Step V
| Ignition State | Pins | Range | Reading(s) |
|---|---|---|---|
| Key off | 73 to 74 | 7.5k–22k Ohms | |
| Key on | 72 to 74 | 4.75–5.25 V |
Key off.
Remove the TCM from the MTM with the 20-Way TCM Vehicle Harness Connector and 20-Way TCM Body Harness Connector connected.
Inspect the TCM side of the 74-Way Transmission Harness Connector, verify the connector is free from contamination and corrosion; the terminals are not bent, spread or loose; and there is no dam-age to the connector body.
Inspect the TCM Seal, verify the seal is properly installed and not damaged.
If contamination or damage is found to the TCM side of the 74-Way Transmission Harness Connector, replace the Transmission Control Module (TCM) and Mechatronic Transmission Module (MTM). 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 or damage is found, Go to Step E
Key off.
Connect the Eaton Breakout Box with 74-Way Eaton Diagnostic Adapter to the TCM side of the 74-Way Transmission Harness Connector.
Measure resistance at the Eaton Breakout Box between Pin 73 and Pin 74. Record reading in table.
Key on.
Measure voltage at the Eaton Breakout Box between Pin 72 and Pin 74. Record reading in table.
Compare reading(s) in table.
If readings are in range, Go to Step F
If readings are out of range, replace Transmission Control Module (TCM). Go to Step V
| Ignition State | Pins | Range | Reading(s) |
|---|---|---|---|
| Key off | 73 to 74 | 7.5k–22k Ohms | |
| Key on | 72 to 74 | 4.75–5.25 V |
Key off.
Remove 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.
Install the MTM Alignment Tool (RR1086TR-1) onto the main housing.
Note: Reference Appendix, Manually Actuate Rail E Procedure.
Using the Rail E Lever, move Rail E to neutral (if necessary).
Shift Rail E into the High Range (fore) engagement position and return to neutral.
Shift Rail E into the Low Range (aft) engagement position and return to neutral.
If Rail E shifts between neutral, High and Low Range, Go to Step G
If Rail E does not shift between neutral, High or Low Range, Go to Step G
Remove the Rail E Detent Plug, Spring and Detent.
Note: Reference Endurant HD Service Manual TRSM0950, Harness Bracket Service Procedure and Rear Housing Disassembly Service Procedure for Rail E Detent location and removal.
Install the MTM Alignment Tool (RR1086TR-1) onto the main housing.
Using the Rail E Lever, move Rail E to neutral (if necessary).
Shift Rail E into the High Range (fore) engagement position and return to neutral.
Shift Rail E into the Low Range (aft) engagement position and return to neutral.
If Rail E shifts between neutral, High and Low Range, contact Eaton Cummins Automated Transmission Technologies at +1 800-826-4357 for further diagnostic instructions. Go to Step V
If Rail E does not shift between neutral, High and Low Range, Go to Step H
If the Rail E Detent could not be removed, Go to Step H
Remove the Rear Housing.
Inspect the Rail E Synchronizer, Shift Rail, Detent and Rear Housing Detent bore.
Contact Eaton Cummins Automated Transmission Technologies for further diagnostic instructions. For Help Line phone numbers, go to Contact Information. Go to Step V
Refer to TRSM0950 Mechatronic Transmission Module (MTM) Service Procedure.
Verify notch on Rail E is facing up.
If MTM was installed with notch on Rail E incorrectly facing down, refer to TRSM0950 Mechatronic Transmission Module (MTM) Service Procedure. Go to Step V
Note: If MTM is installed on the transmission with the notch on Rail E facing down, Fault Code 320 (SPN 5942) FMI 9 sets Active and the transmission will not shift out of neutral.
If MTM was installed with notch on Rail E correctly facing up, Go to Step B
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 320 sets Active during operation, Go to Step A
If a fault code other than 320 sets Active, troubleshoot per the Fault Code Isolation Procedure Index.