I have a 2008 polaris sportsman 500 ho which decided that the battery light would start blinking 20 miles into the trip. Then on came the hot and check engine light. Pulled over let it cool barely turned over. Rode back to truck limping it back. Last stop it had not enough power to turn over. Quick swapped wifes into mine fired right up. Few miles down battery light blinks. Get it home charge battery have it load tested, says it was good. The fan does work when both running and i shut off and turn key but not to start it. I cleaned radiator out carefully with pressure washer, ran it with rad cap off to rid aid bubbles, ive also unplugged heat sensor fan comes right on. Its a carb not efi. Im at a loss. Any help would be greatly appreciated.

 

While running at an idle check charging back to the battery. Should be between 14-14.5 volts on average. If charging is lower than that,battery can't keep up with current needed while in operation to activate fan and can over heat. The blinking battery indicator is the warning sign somethings wrong. Since you've already tried with two batteries more than likely the ecm is faulty. Controls charging,fan operation along with containing most of the circuit breakers.Item #1 on the parts break down.Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse http://www.ebay.com/itm/Polaris-4011568-CONTROL-MODULE-SINGLE-CARB-/281486807210?hash=item4189ebd0aa&vxp=mtr Plus leave the radiator cap off,elevate the front wheels and run until fan cycles on and off several times to remove any trapped air pockets than can cause over heating problems also.Top off the radiator and coolant bottle.

 

So when u say back to the battery do u mean just the battery with a volt meter or is there more to check?

 

While running,battery should have around 13 volts at an idle or so. When engine is revved up battery should get to 14.5- 14.8 volts according to the manual. If you can't get past 13 volts, then this is not enough voltage to run everything including the electronics,fan,etc. Engines can get hot quickly if this happens. Since you've used two different batteries and it does the same thing,you can rule out a battery problem.The ecm module is what usually faults. You can do a general stator test on the yellow charging wires leading to the ecm module if you wish. All yellows should show a small resistance between each other and NO yellow should short to ground.If this checks out I'd replace the ecm module. Plus here's a cheaper ecm for $171 at Partszilla.http://www.partzilla.com/parts/detai...P-4011568.html

 

Thanks so much for responding to me. Could you explain in easier terms what exactly i need to test this and what to set stuff to? Also do i use voltage tester and put it to a ground and then the yellow wire? Basic mechanics i am ok with but electronics are a whole new ballgame. Also how is the install of the ecm? Seems like u just take rack off and the front clip under the headlight and should be able to get at it? Do i need to do anything specific to install it?

 

Yes just remove the front rack,pop the front panel off.Just a simple digital multi meter from Harbor Freight,Walmart,Autozone,etc.. Crank it up,have the meter on dc voltage,check battery reading at an idle,then at around 3000 rpms. Should max out between 14.5-14.8 dc volts if the ecm is charging correctly. With engine OFF,place meter selector on ohms resistance.Pull the connector from the ecm,positive meter lead in one stator yellow wire,negative lead in another one. Should show some resistance reading between all yellows no matter which ones you check. To check for any yellows shorting out,place positive lead on a yellow wire,negative lead to a good ground. NO yellow should short to ground(show 0 ohms) If stator wiring checks out,but charging is not high enough,replace the ecm module. Ecm module just screws on the frame with torque screws,either t20 or t26 if I remember correctly.

 

I will definitely get a tester and do the tests after the 4th of july weekend. Thanks so much for your time and even helping me find the lowest price ecm if thats what it is. I really appreciated it! I kind of hope its the ecm so i can be done troubleshooting it!

 

I take it the ECM takes the place of the rectifier on the older models?

 

Yep and costs 3 times more than a regulator/rectifier since it controls the charging, controls fan operation,has the main circuit breakers,starter lock out,battery protection circuit,hot light indicator control,controls auxiliary electrical among other things..

 

Ok so heres what ive discovered, batery at it is 12.2 with full charge, at idle slowly increases. i can rev it up and it reaches 13.5. Ive put the multimeter in all yellow wires and if its on the right setting they all show roughly 147 with it grounded. I see .5 when i go each one in a different yellow