hey guys. I have a 2008 sportsman 500 efi. been a great bike super reliable. started it up yesterday to drive it into the garage for an oil change. I shut it off to move stuff around so I could fit in inside. when to start it up and it cranked for a couple seconds with no start. turned key off then back on to try again and then nothing. no lights on cluster. put my mutlimeter on battery and had nothing. Now heres the kicker. with the key off or the kill switch off I get 12 volts on battery. when I turn the key on or the kill switch on I get 0v at the battery. Spent all day today reading forum and doing tests. I tried using a wiring schematic for an 07 efi but the connectors don't match up. sorry for the long post but any help would be great. thanks

 

Other than checking the battery itself for a open cell(load test) and connections,I'd go straight to the fuse block where a lot of problems happen. Wires can pull out of the connectors,some can touch,plus there's an inline circuit breaker that can short out and cause power loss to the the fuse block itself. Fuse block can be lifted up to check connections. It's a Delphi type fuse block and if corroded,etc,can be replaced.Per 080 029 036 4 ATO ATC Delphi Fuse Block Panel 4 Gang 12 V Blade Style Fuse | eBay Plus here's a 5 buck manual for your 08 model that may be more helpful.http://polaris-atv.brssm.com/2008-Po...ce-Manual.html

 

ive checked all the fuses and they all have power on both sides while the key is off except the acc one. once I turn the key on there is no power to them. and sometimes if I leave everything on it will randomly power up, when I go to start it, it will click then no lights. Also would you happen to know if that $5 manual has wiring schematics in it. Thanks a lot OPT

 

also I have cleaned all battery connections and ground and even put it on the charger. Could the battery just up and stop working? Ive checked all major connectors and dialectric greased them. I'm pretty confident with my electrical diag ability but just don't understand what would cause my battery to go from 12v key off to 0v key on. thanks again

 

Sounds exactly what a thermal circuit breaker can do if over heating or corroded. It can click off and on. Look up the harness from the fuse panel and the breaker will either be in a sealed pouch or taped to the top of the wiring harness.

 

ive replaced that breaker before when I though it was affecting my fan. key off it has power on both sides, key on nothing. I unplugged it and ohm check it, it has .2 so I think its good. how could I load check my battery? it has fired right up every time until yesterday without any hesitation. thanks

 

Starting Load Test

Adjust voltmeter to DC volts (20 volt range).
Place voltmeter leads to the battery terminals. ( positive to positive and negative to negative)
Watch the voltmeter as you start your atv.
If the voltage drops below 9.5 volts, the battery has very low capacity and should be replaced.

One simple way to test a battery,but best to use a tester that can really put a load on it.

 

if I could get power to the atv when I turn the key on I would test it while cranking but as soon and I turn the key on it drops the battery to 0v. I guess I can pull the battery out and put it in another atv and see if itll start it. thanks for your time and info OPT I appreciate your help.

 

ok I think I'm on to something. I put my battery charger on it and set it to the start setting and I got power and it would click the starter as it would with a low battery. I'm going to buy a new battery Monday and see what happens. I'm guessing its a bad battery but I just don't understand how it started right up then when I went to restart it had no power. weird.

 

Well I'm dumb...new battery and it started right up