I have a formeman 450 es with shifting problems. not allthe time just some time. if you shift normally or slowly works fine both up and down. some time when you put it in a bind it will hang up. when it hangs up instrument panal starts flashing. If you kill it then rock back and forth then it will down shift to neutral and start allover again. may not do it again for week then same thing.I DONT KNOW where shifter mechanism is or if has some typre of selonoid or winding or what. IT ACTS LIKE SOMETHING IS GETTING WEAK LKE NOT ENOUGH FIRE TO MAKE SHIFTER WORK. ONCE YOU ROCK IT GET BACK TO NEUTRAL IT IS GOOD TO GO FOR WEEK MAYBE MONTH BEFORE HAPPENS AGAIN. REV WORKS FINE ALL GEARS WORK FINE DOES NOT SEEM TO BE IN SWITCHES BECAUSE WHEN HANGS UP EVERY TIME YOU PUSH BUTTON IT TRIES TO WORK BUT ACTS LIKE COIL IS WEAK AND WONT PULL WHAT EVER IS IN SHIFTER. if has a selenoid maybe it is just weak cant find the book and dont wont to take to dealer. dont have big bucks to have fixed but live on farm and saves mw a million steps a day HELP

 

Probably a weak battery. They can cause all manner of shifting issues on the es.

 

I have a 99 450es, I have nailed down that my problems come when the engine is reved to high, at 1st I thought it was only happening when I ran here down the road in 5th gear wide open, but then after much troubleshooting I put her in 1st and ran it down the pasture. Walla, happened again. I did some service manual troubleshooting and everything is pointing to the voltage regulator. I can hook a volt meter up to the battery and when I turn on the lights and rev it up the battery voltage actually drops, did a leak test on the battery and again pointed to the v.r. I have to shot off the key, turn back on then rock the ATV shift back to Neutral then restart, I can run all day long at low speeds but once you rev it past that magic point if sends a fault to the ecm and shuts down the system.
Did you fix yours yet and if so what was your fix ?

Hope this helps
Thanks