Fault Code 159: Service Brake Circuit 2
J1939: SA 3 SPN 1088 FMI 9, 13, 19
Overview
The Transmission Control Module (TCM) receives the vehicle’s Service Brake Circuit 2 Air Pressure message from a vehicle Electronic Control Unit (ECU) over the Primary Data Link (J1939A). This information is used to determine transmission operation.
Detection
The TCM monitors Service Brake Circuit 2 Air Pressure 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: Service Brake Circuit 2 Air Pressure message not received for 10 seconds.
FMI 13 - Out of Calibration: Service Brake Circuit 2 Air Pressure message not available for 10 seconds.
FMI 19 – Received Network Data In Error: Service Brake Circuit 2 Air Pressure messages invalid for 10 seconds.
Fallback
FMI 9, 13, 19:
- Amber warning lamp on
- No degraded modes
Conditions to Set Fault Code Inactive
FMI 9, 13, 19: Service Brake Circuit 2 Air Pressure messages received and valid for 10 seconds.
Possible Causes
FMI 9, 13, 19:
- Vehicle Components
- Service Brake Circuit 2 Air Pressure message not enabled
- 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.
Additional Tools
- None
Fault Code 159 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 159 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V
If Fault Code 159 FMI 9, 19 is Active or Inactive, refer to OEM guidelines for repair of the vehicle Service Brake Circuit 2 Air Pressure message (SPN 1088). Go to Step V
If Fault Code 159 FMI 13 is Active, refer to OEM and enable vehicle Service Brake Circuit 2 Air Pressure message (SPN 1088). Go to Step V
If Fault Code 159 FMI 13 is Inactive, Go to Step V
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 159 sets Active, Go to Step A
If a fault code other than 159 sets Active, troubleshoot per Fault Code Isolation Procedure Index.