A 2004 International T444e bus with an Allison 2000 series transmission is experiencing shifting problems. 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 placing the transmission in neutral. This issue arose after resoldering the gauge cluster plug connections.
The BlueFire diagnostic tool reveals an active Spn 2003 FMI 31 code, indicating a communication error between the Transmission Control Module (TCM) and the Engine Control Module (ECM). This diagnosis aligns with online resources pointing to a communication breakdown. Additionally, the BlueFire displays an inaccurate transmission temperature reading exceeding 300 degrees Fahrenheit even at cold startup.
Along with the SPN 2003, several other codes were present. An active code points to a high air intake temperature signal:
- Active Code: 155: 171 0 3 Air Inlet Temperature Signal Out of Range HIGH IAT
Inactive codes include brake switch circuit fault, high exhaust back pressure, and low ECM voltage:
- Inactive Codes:
- 222: 0 247 2 Brake Switch Circuit Fault BRAKE
- 344: 0 34 29 Exhaust Back Pressure Above spec. when engine off or being cranked EBP
- 113: 168 0 4 Electrical System B+ Voltage Out of Range LOW ECM_PWR
- 626: 0 254 8 Unexpected reset fault ECM_PWR
Following advice, the main transmission plug near the tailshaft was inspected and cleaned of oil, but the shift inhibit problem remained. The TCM and its plugs were also examined and found to be clean. The 10-amp TCM fuse is intact, and battery voltage reads above 12.6V at rest and around 13.5V while running. The round bulkhead plug appeared clean upon visual inspection.
While International and Allison documentation has been consulted, understanding the root cause and whether to focus on the ECM or TCM remains challenging.
The primary concern is the SPN 2003 FMI 31 code, signifying the communication failure between the TCM and ECM. This communication breakdown prevents proper transmission operation. Before moving the bus, resolving this issue is crucial to avoid potential damage. While professional assistance is an option, further troubleshooting steps are desired.
Could the SPN 2003 FMI 31 be related to the recent gauge cluster repair? Could there be a wiring issue or a damaged connector related to the data lines between the ECM and TCM? Are there specific tests to pinpoint the communication fault, such as checking continuity or resistance in the wiring harness? Any guidance on further diagnostics would be greatly appreciated.
