A 2004 International T444e with an Allison 2000 series transmission is experiencing persistent transmission issues. The check transmission and shift inhibit lights blink constantly, and the range inhibit light illuminates solid when shifting into reverse (and initially, any forward gear), effectively rendering the transmission in neutral. This problem surfaced after resoldering the gauge cluster plug connections due to intermittent gauge failures. The issue persists even with the dash disconnected and a BlueFire adapter connected.
The BlueFire diagnostic tool reports an Spn 2003 FMI 31 code, indicating a communication problem between the Transmission Control Module (TCM) and the Engine Control Module (ECM). This diagnosis aligns with online resources that associate SPN 2003 FMI 31 with TCM/ECM communication failures. Additionally, the BlueFire displays an abnormally high transmission temperature reading of over 300 degrees Fahrenheit even at cold startup.
Diagnosing SPN 2003 FMI 31: A Breakdown
While the SPN 2003 points towards a communication breakdown, other reported codes might offer further clues. The active code 155 (Air Inlet Temperature Signal Out of Range HIGH IAT), along with several inactive codes related to brake switch circuits, exhaust back pressure, and low ECM voltage, suggest potential broader electrical issues. However, the absence of other active transmission-related codes makes pinpointing the root cause challenging without access to an Allison DOC computer.
Initial troubleshooting steps included checking the main transmission plug near the tailshaft for oil contamination, as recommended by a transmission specialist. Despite cleaning the plug, the shift inhibit problem remains. Further inspection of the TCM and its connectors revealed no visible damage or corrosion. The 10-amp TCM fuse is intact, and battery voltage is within acceptable limits (12.6V at rest, approximately 13.5V running). The round bulkhead plug also appears to be in good condition.
Next Steps in Troubleshooting SPN 2003
While International and Allison documentation provide valuable information, the complexity of the J1939 system can be overwhelming. Determining whether the ECM or TCM is the primary culprit requires a systematic approach.
Possible next steps include:
- Verifying Communication Lines: Thoroughly inspect the wiring harness and connectors between the TCM and ECM for any damage, breaks, or loose connections. Use a multimeter to test for continuity and resistance in the communication lines.
- Checking Power and Ground Supply: Ensure both the TCM and ECM are receiving proper power and ground. Use a multimeter to measure voltage at the respective pins.
- Consulting Schematics: Refer to detailed wiring diagrams for the specific bus model to identify all relevant components and connections in the communication network.
Resolving the SPN 2003 Code: Seeking Expert Assistance
Given the complexity of the issue and the potential for further damage, seeking professional assistance from a qualified technician with expertise in J1939 systems may be necessary. While gaining familiarity with the bus’s electrical system is valuable, attempting to move the vehicle without addressing the underlying transmission problem is strongly discouraged.
A proper diagnosis and repair will ensure the safe and reliable operation of the vehicle. Remember, prioritizing safety and seeking professional help when needed is crucial in maintaining your vehicle.
