hi.this is my first post on this site.just a little back ground i have a 400ex which i have raced and rebuilt. i came across a good deal on a 2001 TRX500FA it was free. when i got the bike it was stuck in low gear with the blink rate duration at .5sec.i traced the problem to the angle sensor resistance between the Y/R and the Y/Bu terminals. i got a new angle sensor the bike ran and shifted for about 4 hr. then it happend again so i put anouther new sensor in and it shifted for 6hr.each time the sensor is shorted the the reduction gear is locked up.so as it sits the when i start the bike it studders in reverse and is stuck in low gear. so i guess what iam asking is somthing electritly or mechaniclly FN up my angle sensor.

 

If yo have the factory repair manual, it is easier to find the problem, because the quad has a self diagnostic mode.

 

I found a complete repair manual for this type of machine on the web page ATV NATION. (132 megs)

It has all the code an diognistics.

Good Luck