Fault Code 155: Park Brake Switch
J1939: SA 3 SPN 70 FMI 9, 13, 14, 19
Overview
The Transmission Control Module (TCM) receives the vehicle’s Parking Brake Switch message from a vehicle Electronic Control Unit (ECU) over the Primary Data Link (J1939A). This information is used to determine the vehicle state.
Detection
The TCM monitors Parking Brake Switch messages. If messages are not received or are invalid, the fault is set Active.
Conditions to Set Fault Code Active
FMI 9 – Abnormal Update Rate: Parking Brake Switch message not received for 5 seconds.
FMI 13 – Out of Calibration: Parking Brake Switch message not available for 5 seconds.
FMI 14 – Special Instructions: Parking Brake Switch message not received during launch for 1 second.
FMI 19 – Received Network Data in Error: Parking Brake Switch messages invalid for 5 seconds.
Fallback
FMI 9, 13, 14, 19:
- Amber warning lamp on
- Urge to Move and Creep Mode prohibited
Note: Vehicle may have additional fallback modes. Refer to OEM.
Conditions to Set Fault Code Inactive
FMI 9, 13, 14, 19: Parking Brake Switch messages received and valid for 10 seconds.
Possible Causes
FMI 9, 13, 14, 19:
- Vehicle Components
- Parking Brake Switch message not enabled
- Parking Brake Switch internal failure
- Other vehicle ECU(s) faulted
- Vehicle Harness - Primary Data Link (J1939A)
- Wiring shorted to power, shorted to ground or open
- Terminals bent, spread, corroded, or loose
Note: Refer to OEM for troubleshooting a failed system.
Fault Code 155 Troubleshooting
Set vehicle parking brake and chock wheels.
Record transmission fault codes, FMIs, occurrences, and timestamps from Service Activity Report created during the Diagnostic Procedure.
If Fault Code 155 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V
If Fault Code 155 FMI 9, 14, 19 is Active or Inactive, Go to Step B
If Fault Code 155 FMI 13 is Active, refer to OEM and enable vehicle Parking Brake Switch message (SPN 70). Go to Step V
If Fault Code 155 FMI 13 is Inactive, Go to Step V
Key on with engine running.
Allow air pressure to build to governor cut off.
Key off.
Key on with engine off.
Connect ServiceRanger.
Go To “Data Monitor”.
Select “Status”.
Select “Parking brake switch status”.
Select all “- 70” SPN sources.
Note: Not all sources will indicate a value.
Monitor 70 - Parking brake switch status value. Record reading in table.
Depress and hold service brake.
Release vehicle parking brake.
Monitor 70 - Parking brake switch status value. Record reading in table.
Set vehicle parking brake.
Compare reading(s) in table.
If readings are out of range, refer to OEM guidelines for repair of the vehicle Parking Brake Switch message (SPN 70). Go to Step V
If readings are in range and no fault was found, the intermittent nature of the fault makes it likely that the problem is in the vehicle Parking Brake Switch message (SPN 70). Contact OEM for further diagnostic instructions. Go to Step V
| Parking Brake State | Parameter | Range | Reading(s) |
|---|---|---|---|
| Set | 70-Parking brake switch status | Set | |
| Released | 70-Parking brake switch status | Not set |
Key off.
Reconnect all connectors and verify all components are properly installed.
Key on with engine off.
Connect ServiceRanger.
Go To “Fault Codes”.
Select “Clear All Faults”.
Operate vehicle and attempt to reset the fault code or duplicate the previous complaint.
Check for fault codes using ServiceRanger.
If no fault codes set and vehicle operates properly, test complete.
If Fault Code 155 sets Active, Go to Step A
If a fault code other than 160 sets Active, troubleshoot per Fault Code Isolation Procedure Index.