Endurant HD
TRTS0950 EN-US
|
July 2024 - B

Fault Code 975: Reverse Output

J1939: SA 3 SPN 767 FMI 3, 4, 5, 6, 12, 14, 31

Overview

The Transmission Control Module (TCM) is configurable to provide a Reverse Output signal to other circuits or devices on the vehicle for an application specific vehicle operation. When Reverse is selected on the Driver Interface Device and is confirmed from transmission rail position and speed sensors the TCM will provide a 12-volt hardwired output signal to an application specific vehicle circuit or device.

The TCM is equipped to receive 4 switch inputs and control 3 relay outputs that can be configured in an Input/Output (I/O) Package to support this vocational feature. The Reverse Output circuit is connected to the TCM in the 20-Way TCM Body Harness Connector. The Reverse Output circuit is installed by the OEM or body builder. Reference Input / Output Calibration of the Appendix for recommended Reverse Output circuit wiring diagrams.

Detection

The TCM monitors the hardwired Reverse Output circuit signal. If the signal is out of range, the fault is set Active.

Conditions to Set Fault Code Active

FMI 3 – Voltage Above Normal or Shorted High: Reverse Output circuit signal shorted to power for 5 seconds.

FMI 4 – Voltage Below Normal or Shorted Low: Reverse Output circuit signal shorted to ground for 5 seconds.

FMI 5 – Current Below Normal or Open Circuit: Reverse Output circuit open for 5 seconds.

FMI 6 – Current Above Normal or Grounded Circuit: Reverse Output circuit current out of range for 5 seconds.

FMI 12 – Bad Intelligent Device: TCM has detected an internal processing error.

FMI 14 – Special Instructions: The TCM detected invalid I/O Package calibration.

FMI 31 – Condition Exists: The TCM detected invalid I/O Package calibration.

Fallback

All FMIs:

  • Amber warning lamp on
  • Devices requiring Reverse Output signal may not function

Conditions to Set Fault Code Inactive

FMI 3: Reverse Output circuit not shorted to power for 10 seconds.

FMI 4: Reverse Output circuit not shorted to ground for 10 seconds.

FMI 5: Reverse Output circuit not open for 10 seconds.

FMI 6: Reverse Output circuit current in range for 10 seconds.

FMI 12: Key cycle and fault condition no longer exits.

FMI 14, 31: Valid I/O Package calibration file is configured in TCM.

Possible Causes

FMI 3, 4, 5, 6:

  • Vehicle Reverse Output device
  • Vehicle Reverse Output wiring
    • Reverse Output is configured “Enabled” in the TCM but wiring is not installed.
    • Wiring shorted to power, shorted to ground or open.

FMI 12:

  • TCM
    • Software issue
    • Internal failure

FMI 14, 31:

  • TCM
    • Invalid I/O Package calibration file configured in TCM

Component Identification

_Graphics/LineArt/TRTS0960_FC975_ID.png

1. 20-Way TCM Body Harness Connector

2. Transmission Control Module (TCM)

Fault Code 975 Troubleshooting

A
Purpose:Identify Transmission Model.

  1. Set vehicle parking brake and chock wheels.

  2. Record transmission model from Service Activity Report created during the Diagnostic Procedure.

B
Purpose:Check for Active or Inactive fault codes.

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

C
Purpose:Verify Reverse Output Signal configured in the TCM and installed on the vehicle.

  1. Key off.

  2. Allow TCM to perform a complete power down.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Go to “Configuration”.

  6. Select “Options”.

  7. Record the “Reverse Output Signal” "Current Value" in table.

  8. Record the “Reverse Output Signal” installed on the vehicle in table.

    Note: The vehicle's Reverse Output Signal (Disable or Enable) is determined by OEM. Refer to the OEM regarding the Reverse Output Signal installed on the vehicle.

  9. Compare reading(s) in table.

  • If “Reverse Output Signal” is not configured correctly, select the correct configuration from the “New Value” drop down, select “Apply” and follow on screen prompt. Go to Step V

  • If FC975 is Active and “Reverse Output Signal” is configured correctly, refer to OEM guidelines for repair or replacement of the Reverse Output signal wiring. Go to Step V

LocationReverse Output Signal
TCM (ServiceRanger)
Vehicle
D
Purpose:Check for Active or Inactive fault codes.

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

  • If Fault Code 975 FMI 3, 4, 5, 6 is Active, Go to Step E

  • If Fault Code 975 FMI 3, 4, 5, 6 is Inactive, the intermittent nature of the fault makes it likely that the problem is in the Reverse Output circuit. Go to Step F

    Note: Reverse Output circuit and wiring are installed by OEM or body builder.

  • If Fault Code 975 FMI 12 is Active replace, Transmission Control Module (TCM). Go to Step V

  • If Fault Code 975 FMI 12 is Inactive, Go to Step V

  • If Fault Code 975 FMI 14 or 31 is Active, 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 975 FMI 14 or 31 is Inactive, Go to Step V

E
Purpose:Verify Reverse Output Signal configuration with ServiceRanger.

  1. Key off.

  2. Allow TCM to perform a complete power down.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Go to “Configuration”.

  6. Select “Options”.

  7. Record the “Reverse Output Signal” Current Value.

  • If "Reverse Output Signal" Current Value indicates “Disabled” and Reverse Output signal circuit is properly installed and wired, select “Enabled" and follow on-screen prompts. Go to Step V

  • If "Reverse Output Signal" Current Value indicates “Enabled” and Reverse Output signal circuit is properly installed and wired, Go to Step F

F
Purpose:Verify Input/Output Package type with ServiceRanger.

  1. Key on with engine off.

  2. Connect ServiceRanger.

  3. Go To “Configuration”.

  4. Select “Calibrations” tab.

  5. Record "I/O Package" Current Value.

  • Based on I/O package configured refer to I/O circuit schematic indicated in table.Contact OEM or body builder for repair or replacement of Reverse Output signal circuit. Go to Step V

    Note: Reverse Output circuit and wiring are installed by OEM or body builder.

Fault Code 975: Reverse Output
Package # and Description20-Way TCM Body Connector Pin(s)Component(s)
Input / Output Calibration Package 1: Neutral Output + PTO 1 + Reverse Output1Reverse Output RelayReverse Output Fuse 2 AmpChassis Ground
Input / Output Calibration Package 8: PTO 1 + Reverse Output + Rock Free Mode1
Input / Output Calibration Package 10: Reverse Output1
Input / Output Calibration Package 11: PTO 1 + Reverse Output1
Input / Output Calibration Package 24 and 27: Force Neutral + Neutral Output + Reverse Output and Hold Neutral + Neutral Output + Reverse Output2
Input / Output Calibration Package 30: Reverse Output and Secondary Shift Mode1
Input / Output Calibration Package 31: Reverse Output + Rock Free Mode1
Input / Output Calibration Package 35: Reverse Output + Neutral Output1
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.