2003 freightliner century. 12.7 Detroit non-egr with a 3 pedal autoshift (has clutch pedal. Been a flawless truck for me. Ran it last 3 years, has never missed a shift, always engages in gear right away. Truck has always had 3 faults in the display but no check engine light. Previous owner put a new x-y shifter on about 40k miles ago. Software updated. New clutch at the same time. Last week, the speedometer quit going down the road, check engine light comes on, stuck in 10 gear. Shut truck off, it shifts properly for about 10 miles, and acts up again. This continued for several attempts. 6 faults on the displayCodes Sid 216 Fmi 14, pid 84 Fmi 12 (speedo sensor). Replaced sensor with 2 different sensors, still won’t communicate. Took it off, tried tapping it on metal, and waved a wrench by the sensor, to see if the speedometer would work, it does not. The gear in the yoke is tight. Yoke is tight. I replaced the wiring harness from the TCU to the sensors, still a check engine light and won’t shift. All fuses replaced, problem still persists. Cleaned all battery terminals. Batteries are good, alternator is good. Tried an ecm and tcu off a 2002 century with a 12.7/3 pedal autoshift, same problem. I’m not saying the ecm/tcu off that other truck are good, but tried it anyway. What else could I try? Is my TCU bad? Any help I appreciate. I’ve read every forum on this matter and after about 10 replies we never get an update.
The old plastic junk speedo p/u sensor that may have broke off on the inside of the tail of transmission?
This one does not thread in. This is the one that slides in, has an o-ring at the base and is held in by a bracket and a bolt.
Oddly enough, a few hours after posting this we fixed our issue. For the sake of someone down the road looking for an answer, it turned out to be a wire wore in 2 up by the starter area.
