There are error codes for the forward and reverse pedal sensor being above and below normal and out of range/out of calibration. It's a ground and +5 volt operated device. So if the sensor (output) from a pedal is shorted to ground or plus 5 (or above) you'd get an error code. I would imagine the controller's input from the pedals has a small pull up or pull down resistor on it such that if that wire goes open, you'd get an error (never seen this not done, but don't have explicit knowledge about this design). The sensor supply voltage is also monitored and there are error codes for that having a problem or being out of range.
The instrument controller (dash board or ICC) has 34 errors it can detect, the transmission control unit (TCU) has 28 errors it can detect and the engine control unit (ECU) has 62 errors it can detect. All these have displays on the dash.
There are also a number of other measurements (things you can read from the controller) that can be made by a dealer (manual shows 11 pages of them, and then 40+ pages with details on the faults), and I suspect there are other error codes that are not listed in the manual (either they are rare or software updates added them).
So what's my point? Check things, but don't go too nuts about it. There is also the good news/bad news about any computer controller tractor. It takes a computer to fix a computer, but the computer can identify a lot of problems with wiring and sensors that could not be identified before. So if you've checked the obvious there is a point where the dealer has to show up and plug in some stuff. I know this isn't directly helping you, but if it keep you from tearing up things to check other things, it might help.
I suspect the long term success of the computer controlled tractor will boil down to how much does it cost to have the dealer come out, plug the tractor into the mother ship, and see what the problem is. I'm also curious if you'll be able to by replacement controllers in 15 years. It's not a technical problem, even if they redesign the controller boards. Time will tell.
Sorry I can't be more helpful or specific.
Pete
