Endurant HD
TRTS0950 EN-US
|
October 2024 - B

Fault Code 144: Transmission Secondary Shift Down Selector

J1939: SA 3 SPN 3656 FMI 2, 9, 10, 11, 13, 19, 31

Overview

The Transmission Control Module (TCM) receives the vehicle’s Primary Automated Driving System (ADS) Transmission Requested Gear message from the vehicle ADS Electronic Control Unit (ECU) over the Primary Data Link (J1939A). This information is used to verify the transmission Shift Mode from the transmission driver interface device to the vehicle ADS ECU.

The TCM also receives a Secondary Automated Driving System (ADS) Transmission Requested Gear message from the vehicle ADS Electronic Control Unit (ECU) over the Primary Data Link (J1939A). This redundancy allows the TCM to maintain transmission function in a degraded mode in the event either message is not available.

Detection

The TCM monitors Secondary ADS Transmission Requested Gear messages. If messages are not received or are invalid, the fault is set Active.

Conditions to Set Fault Code Active

FMI 2 – Data Erratic: Secondary ADS Transmission Requested Gear messages out of range for 5 seconds.

FMI 9 – Abnormal Update Rate: Secondary ADS Transmission Requested Gear message not received for 5 seconds.

FMI 10 - Abnormal Rate of Change: Secondary ADS Transmission Requested Gear message error for 5 seconds.

FMI 11 - Root Cause Unknown: Secondary ADS Transmission Requested Gear message not received for 5 seconds.

FMI 13 – Out of Calibration: Secondary ADS Transmission Requested Gear messages not available for 5 seconds.

FMI 19 – Received Network Data In Error: Secondary ADS Transmission Requested Gear messages invalid for 5 seconds.

FMI 31 - Condition Exists: Secondary ADS Transmission Requested Gear message error for 5 seconds.

Fallback

All FMIs:

  • Amber warning lamp on
  • ADS operation prohibited

Conditions to Set Fault Code Inactive

All FMIs: Secondary ADS Transmission Requested Gear messages received and valid for 10 seconds.

Possible Causes

All FMIs:

  • Vehicle Components - Vehicle ECU(s)
    • Secondary ADS Transmission Requested Gear message not enabled
    • Other vehicle ECU(s) faulted
  • Vehicle Harness - Primary Data Link (J1939A)
    • Shorted to power, shorted to ground or open circuit
    • Terminals bent, spread, corroded, or loose

Note: Refer to OEM for troubleshooting a failed system.

Additional Tools

  • None

Fault Code 144 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 144 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V

  • If Fault Code 144 FMI 2, 9, 10, 11, 19, 31 is Active or Inactive, refer to OEM guidelines for repair of the vehicle Secondary ADS Transmission Requested Gear message (SPN 3656). Go to Step V

  • If Fault Code 144 FMI 13 is Active, refer to OEM and enable vehicle Secondary ADS Transmission Requested Gear message (SPN 3656). Go to Step V

  • If Fault Code 144 FMI 13 is Inactive, Go to Step V

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.