I have problems with my Honda 2004 TRX500 atv and would appreciate any suggestions.  A few months ago I was out ice fishing and the machine went into limp mode - 1st gear only, high rpm, maximum speed = 12mph.  Took it into the dealer and they said the ecu went out - replaced it with a new one.  Went out again, machine worked well for one day, next day it was back into limp mode.  Back into the dealership, the ecu was out again.  There are no codes, just flashing fast.  They have checked all grounds, switches, wiring for continuity and voltage.  The shift sensor and wiring are good.  The shift motor is supposed to have <100ohms, it is at 102ohms.  They tell me they cannot test if the shift motor is bad, only by replacing it.  They have recommended a new control unit ($210) and a motor assy control ($213), but can't guarantee these parts will fix my machine.  The best part is once they put them on my atv, the parts are mine whether they fix the problem or not.  I have been in contact with honda numerous times and their response is pretty much pay for the parts and hope it fixes the problem.  Any suggestions would be apprectiated.

- Extremely Frustrated    

Since my atv is a 1985 it has absolutely no emissions or other electronic "technical advances" to break. However, I feel your pain and would recommend checking on ebay for used parts. Even though this is a newer quad, sometimes they get parted out because they are totaled in accidents.  

yeaah it does sound like the shift motor.

have you tested the shift motor while running and shifting, it may be losing continuity intemittently  

Thanks for the suggestions - will do and post what the problem was (if we can find what is wrong with it LOL).