Fault Code 163: Demanded Brake Application Pressure

J1939: SA 3 SPN 8484 FMI 9, 13, 19

Overview

The Transmission Control Module (TCM) receives the vehicle’s Demanded Brake Application Pressure signal message over the Primary Data Link. This information is used to determine transmission operation.

Detection

The TCM monitors the Demanded Brake Application Pressure signal message. If a failure is detected the fault is set Active.

Conditions to Set Fault Code Active

FMI 9 - Abnormal Update Rate: Demanded Brake Application Pressure signal not received for 10 seconds.

FMI 13 - Out of Calibration: Demanded Brake Application Pressure message not available for 5 seconds.

FMI 19: Demanded Brake Application Pressure message invalid for 5 seconds.

Fallback

FMI 9, 13, 19:

  • Amber warning lamp on
  • Urge to Move and Creep Mode prohibited

Conditions to Set Fault Code Inactive

FMI 9, 13, 19: Demanded Brake Application Pressure signal received and valid for 10 seconds.

Possible Causes

FMI 9, 13, 19:

  • Vehicle Components
    • Module(s)
    • Demanded Brake Application Pressure Sensor
    • Primary Data Link

Additional Tools

  • None

Fault Code 163 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 163 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V

  • If Fault Code 163 FMI 13 is Active, refer to OEM and enable vehicle Demanded Brake Application Pressure SPN 8484. Go to Step V

  • If Fault Code 163 FMI 13 is Inactive, Go to Step V

  • If Fault Code 163 FMI 9 or 19 is Active or Inactive, Go to Step B

B
Purpose:Monitor Demanded Brake Application Pressure signal message.
  1. Key on with engine running.

  2. Allow air pressure to build to governor cut off.

  3. Key off.

  4. Key on with engine off.

  5. Connect ServiceRanger.

  6. Go To “Data Monitor”.

  7. Select “Pressure”.

  8. Select “Demanded brake application pressure”.

  9. Select all of the “- 8484” SPN sources.

    Note: Not all sources will indicate a value.

  10. Monitor 8484 - Demanded brake application pressure value. Record reading in table.

  11. Depress and hold service brake.

  12. Monitor 8484 - Demanded brake application pressure value. Record reading in table.

  13. Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of the Demanded brake application pressure 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 Demanded brake application pressure signal message. Contact OEM for further diagnostic instructions. Go to Step V

Service Brake StateParameterRangeReading(s)
Released8484 - Demanded Brake Application Pressure0 PSI
Depressed8484 - Demanded Brake Application PressureGreater Than 0 PSI
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.