Endurant HD
TRTS0950 EN-US
|
November 2024 - B

Fault Code 172: Secondary Engine Speed

J1939: SA 3 SPN 723 FMI 9, 13, 19

Overview

The Transmission Control Module (TCM) receives the vehicle’s Engine Speed message over the Primary Data Link and Secondary Engine Speed message over the Secondary Data Link. The TCM uses the Engine Speed as the primary engine speed message during normal transmission operation. If the Engine Speed becomes unavailable, the Secondary Engine Speed allows the transmission to operate in a degraded mode.

Detection

The TCM monitors the Secondary Engine Speed message. If the message is not received or invalid, the TCM sets the fault code active.

Conditions to Set Fault Code Active

FMI 9 - Abnormal Update Rate: Secondary Engine Speed message not received for 5 seconds.

FMI 13 – Out Of Calibration: Secondary Engine Speed message not available for 5 seconds.

FMI 19 – Received Network Data In Error: Secondary Engine Speed messages invalid for 5 seconds.

Fallback

All FMIs:

  • Amber warning lamp on
  • No degraded modes
  • If Fault Code 115, 165 or 171 is Active:
    • Non neutral modes prohibited
    • PTO Mode prohibited
  • If Fault Code 115, 165 or 171 is Active and vehicle is moving:
    • Red stop lamp on
    • Upshifts prohibited

Note: Engine fallback modes will vary.

Conditions to Set Fault Code Inactive

All FMIs: Secondary Engine Speed signal received and valid for 10 seconds.

Possible Causes

All FMIs:

  • Vehicle Components
    • Module(s)
    • Engine speed sensor
    • J1939 Data link

Note: Refer to OEM or engine manufacture for troubleshooting a failed system.

Additional Tools

  • None

Fault Code 172 Troubleshooting

A
Purpose:Check for Active or Inactive fault codes.

  1. Set vehicle parking brake and chock wheels.

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

  • If Fault Code 172 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V

  • If Fault Code 172 FMI 13 is Active, refer to OEM and enable vehicle Engine speed sensor #2 SPN 723 signal message. Go to Step V

  • If Fault Code 172 FMI 13 is Inactive, Go to Step V

  • If Fault Code 172 FMI 9 or 19 is Active or Inactive, Go to Step B

B
Purpose:Verify Engine speed sensor #2 signal message.

  1. Key on with engine on at idle.

  2. Connect ServiceRanger.

  3. Go To “Data Monitor”.

  4. Select “Speed”.

  5. Select “Engine speed sensor #2”.

  6. Select all of the SPN “- 723” sources.

    Note: Not all sources will indicate a value.

  7. Monitor vehicle tachometer and record engine idle RPM value in table.

  8. Monitor ServiceRanger and record “Engine speed sensor #2” RPM value in table.

  9. Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of the Engine speed sensor #2 signal message. Go to Step V

  • If readings are in range, no fault was found. The intermittent nature of the fault makes it likely that the problem is in the Engine speed sensor#2 signal message. Contact OEM for further diagnostic instructions. Go to Step V

Engine Speed Signal SourceRangeReading(s)
Vehicle TachometerIdle RPM
723 - Engine Speed Sensor #2Within 150 RPM of Engine Idle
V
Purpose:Verify repair.

  1. Key off.

  2. Reconnect all connectors and verify that 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.