Moderators: robnewyork, bassiclyLouDog, gameboy

This is my third yk31c controller and the first time I have ever had an issue.

Been riding the razor for two days and today all of a sudden it went full voltage to motor as soon as i turned it on. Had to pull a cable off a battery to get it to stop. to troubleshoot I unhooked everything but the motor and batteries and it still goes full throttle. I pulled the controller apart and there is no black/fried spots or smells. :?:

500w unite motor
36v 10ah batteries
12ga wiring

Try checking the capacitors in the controller and see if any of them are leaking or bulging. The Chinese controllers use the cheapest caps as possible. They are usually made of aluminum instead of copper.

When I get a cheap controller, one of the first things I do is strip it down and replace the caps with with low ESR Panasonic or Nichicon capacitors.
Hi Quinc,

Use a multimeter, set the meter to read in the high ohms range, somewhere above 10k and 1m ohms. Touch the meter leads to the corresponding leads on the capacitor, red to positive and black to negative. The meter should start at zero and then moving slowly toward infinity.

Usually it easier to just buy a higher amp controller. The YK43B is my favorite and it looks like they are available again on eBay: ... 0005.m1851

(Here's the item description showing that it handles 24 - 60 volt) ... cureDesc=0

A big heads up though, the YK43B will dump a HUGE amount of amps to your motor! You will pop a wheelie if your not careful!

However, if your like me and you like to do things just "because", you can replace the fets to increase power, but it's a lot of work and you need a good soldering iron. The shunt can be modded to increase power. summerbear48 did a nice write up here:

Well son of a bitc.... It happened again. Rode the gokart for the last two days probably over 1 an hour on it. Today I plugged it in to charge and as soon as I plugged it in, it went full throttle again.. Doesn't matter if everything else is unplugged she still goes.. Wondering if it could be my power switch or possibly something else? 24v throttle with 36v controller? Luckily i got the last two off amazon and am able to return them. :)
Quinc wrote: 24v throttle with 36v controller?
That could be your problem. If the hall sensor is expecting 24v and it's getting 32v, it might be activating because of that. robnewyork would be the guy to ask, but I haven't noticed him around for the last few months. (I hope that he didn't get hurt with one of his projects).

I would try swapping with a 36v controller if you have one, otherwise do the Amazon return.
Quinc wrote:I talked to Rob, he is alive and well. His account got locked out and he created a new one but since no moderators are around they cant approve his posts..
Did rob have any suggestions? BTW, where are the moderators?

Thanks for letting me know that rob is OK, (chuckle), robnewyork, if your reading this, you understand our concerns about your safety! ;) :lol:

My inaugural run happened early this evening after[…]