Endurant HD
TRTS0950 EN-US
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October 2024 - B

Fault Code 987: Rock Free Mode Switch

J1939: SA 3 SPN 12939 FMI 3, 4, 5, 6, 11, 12, 13, 14, 20, 31

Overview

The Endurant HD Pro transmission incorporates a Rock Free Mode feature that allows the driver to perform a vehicle “rocking” maneuver by depressing and releasing the vehicle accelerator pedal. This maneuver is useful in situations where the vehicle’s wheels are stuck in terrain depressions that are preventing vehicle progress. When Rock Free Mode is required the Transmission Control Module (TCM) receives a request (Input) for Rock Free Mode operation, determines if operating conditions are suitable, implements the change, and supplies a signal (Output) notification. Reference Endurant HD Driver Instructions TRDR0955 for Rock Free Mode operation.

The TCM can be configured to activate Rock Free Mode with messages over the vehicle Primary Data Link J1939A or from a switch circuit hardwired directly to the TCM. 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 various vocational features.

If the TCM is configured to "J1939 Message" Rock Free Mode operation messages are exchanged between the TCM and a OEM vehicle ECU. If the TCM is configured to " TCM Hardwired Switch", Rock Free Mode operation is controlled by Input and Output signals from a hardwired switch circuit.

The Rock Free Mode circuit is connected to the TCM in the 20-Way TCM Body Harness Connector. The Rock Free Mode circuit is installed by the OEM or body builder. Reference Input / Output Calibration in the Appendix for recommended Rock Free Mode circuit wiring diagrams.

Detection

The TCM monitors the Rock Free Mode Switch hardwired circuit input 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: Rock Free Mode Switch circuit output signal shorted to power for 5 seconds.

FMI 4 – Voltage Below Normal or Shorted Low: Rock Free Mode Switch circuit output signal shorted to ground for 5 seconds.

FMI 5 – Current Above Normal or Open Circuit: Rock Free Mode Switch circuit open for 5 seconds.

FMI 6 – Current Above Normal or Grounded Circuit: Rock Free Mode Switch circuit output current out of range for 5 seconds.

FMI 11 – Root Cause Unknown: The TCM detected invalid I/O Package calibration.

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

FMI 13 – Out of Calibration: The TCM detected invalid I/O Package calibration.

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

FMI 20 – Data Drifted High: Rock Free Mode Switch circuit input signal out of range (4.00–5.25 V) for 5 seconds.

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

Fallback

All FMIs:

  • Amber warning lamp on
  • No degraded modes
  • Rock Free Mode will not function

Conditions to Set Fault Code Inactive

FMI 3: Rock Free Mode Switch circuit not shorted to power for 10 seconds.

FMI 4: Rock Free Mode Switch circuit not shorted to ground for 10 seconds.

FMI 5: Rock Free Mode Switch circuit not open for 10 seconds.

FMI 6: Rock Free Mode Switch circuit output current in range for 10 seconds.

FMI 11, 12: Key cycle and fault condition no longer exits.

FMI 13, 14, 31: Valid I/O Package calibration file is configured in TCM.

FMI 20: Rock Free Mode Switch circuit input signal in range for 10 seconds.

Possible Causes

FMI 3, 4, 5, 6, 20:

  • Vehicle Harness - Rock Free Mode Switch Circuit
    • Shorted to power, shorted to ground, or open circuit

FMI 11, 13, 14, 31:

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

FMI 12:

  • TCM
    • Internal failure
    • Software issue

Fault Code 987 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 987 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V

  • If Fault Code 987 FMI 3, 4, 5, 6 or 20 is Active, Go to Step B

  • If Fault Code 987 FMI 3, 4, 5, 6 or 20 is Inactive, the intermittent nature of the fault makes it likely that the problem is in the Rock Free Mode Switch circuit. Go to Step C

    Note: Rock Free Mode Switch circuit wiring is installed by OEM or body builder.

  • If Fault Code 987 FMI 12 is Active, replace Transmission Control Module (TCM). Go to Step V

  • If Fault Code 987 FMI 12 is Inactive, Go to Step V

  • If Fault Code 987 FMI 11, 13, 14, 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 987 FMI 11, 13, 14, 31 is Inactive, Go to Step V

B
Purpose:Verify Rock Free Mode configuration with ServiceRanger.

  1. Key on.

  2. Connect ServiceRanger.

  3. Go To “Configuration”.

  4. Select “Options”.

  5. Record "Rock-Free Mode" Current Value.

  • If "Rock-Free Mode" Current Value indicates “Disabled” and Rock Free Mode Switch circuit is properly installed and wired, select “TCM Hardwired Switch" and follow on-screen prompts. Go to Step V

  • If "Rock-Free Mode" Current Value indicates “TCM Hardwired Switch” and Rock Free Mode Switch circuit is properly installed and wired, Go to Step C

C
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 Rock Free Mode Switch signal circuit.Go to Step V

    Note: Rock Free Mode Switch signal circuit wiring is installed by OEM or body builder.

Fault Code 987: Rock Free Mode Switch
Package # and Description20-Way TCM Body Connector Pin(s)Component(s)
Input / Output Calibration Package 2 in TRIG2630: Rock Free Mode + Secondary Shift Mode 35 6Rock Free Momentary SwitchRock Free RelayRock Free Fuse 2 AmpChassis Ground
Input / Output Calibration Package 7 in TRIG2630: PTO 1 + Rock Free Mode + Secondary Shift Mode356
Input / Output Calibration Package 8 in TRIG2630: PTO 1 + Reverse Output + Rock Free Mode356
Input / Output Calibration Package 9 in TRIG2630: Rock Free Mode356
Input / Output Calibration Package 29 in TRIG2630: PTO 1 + Rock Free Mode 3 5 6 15
Input / Output Calibration Package 31 in TRIG2630: Reverse Output + Rock Free Mode 3 5 6
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.