My Borther-in-law has an 05 Bruin 350 and while riding last weekend the 4wd fuse blew. We changed it with the spare and it blew when the key was turned on. Then we bought 5 more and washed the bike, checked the wiring and everything visibly and tried it again, blew another by turning on the key. We also unhooked the wires from the front diff and it still blew the next one. Anyone have any clue what could cause this? I am not sure where to look from there...

 

Theres a short in the wire , somewhere between the fuse and the load, or it could be the load too. (the motor for the 4wd)
Itll help if you have a wiring diagram, to show you which color wires to focus on. Could be a pinched wire, or could be water in a connector.
There are ways of finding the problem but it requires some equipment , none of which is expensive.
Do you have a volt ohm meter, or a low voltage test light?
If you dont have the wiring diagram i could email a .jpeg of one. If you want it, pm me, with your email address.
What were the circumstances of the fuse blowing...was he in deep water, or just got done going thru some thick brush. You can look at the connectors and the wires going to the 4wd motor, and look for bare spots touching the frame, or connectors full of water.

 

maybe you should use some of that grease that you put on electrical wires like when you wire a trailer I forget the name of it though

 

Dielectric Grease

 

I unhooked the motor on the front diff and it still does it, we were trail riding and he was about to go into some mud (maybe 6 inches deep) and it went out.

 

yeah dielectric grease thats the stuff we use it on everything electrical just about

 

Sounds like the motor is good. Youve got a wiring or switch issue. Youll need an ohm meter or test light to trouble shoot it further.
You can get the test light at home depot for less than 2 bucks. Just clip it accross the terminals where the fuse is held, and turn on the key. When the light of the test light is lit, theres a short circuit. Wiggle wires and connectors till the light goes out, and youve found the short. If wiggleing the wires doesnt do the trick, then it could be the switch or a connector.
If you go to nyrocs site,here
and go to the general tips section, theres a tip about doing this, and has pictures.

 

Thanks hondabuster, I have a multimeter, I will put that in there with a continuity test and the 4x4 off, that should work right? I will go over to nyroc, I am a member there too. I took the switch itself apart, all is fine there as well, so its wiring or I saw in the manual that it could be the ECM as well, hope thats not it! I will let you know tomorrow what I find!

 

If youre gonna use a multimeter, theres two ways you can use it. I like the test light, because its much more visible and its either on or off.
You can use volts dc, and have the key on, and when the volts drop to zero youve found the problem, or you can use the ohmeter (which is what i recommend), and do not turn the key on (you dont want voltage running thru the meter when its in the resistance settings). Itll read short(continuity), and will show open when you find the problem.
Try wiggling small sections of wire at a time, if you wiggle too much of a length, it becomes difficult to find the short.
I looked at the wiring diagram, and i dont see the ecm being an issue on this one. Im betting its on the BR/R wire or the BR/W wire.
This only happens in 4wd right? It doesnt blow a fuse in 2wd? If the fuse blows in either position, itll be the BR/R wire.
Let us know what you find.

 

Found it today, I started following all the wires and found that the exhaust had melted into one of the harnesses and the took the insulation off two wires! Taped it all up again and hook the battery back up and it was fine! I only followed the wires on the left side last time, but I noticed that some of the wires on the front diff continue around the front then go up on the right side by the exhaust. Thanks for the help guys.