I am living in southern Indiana and own a 2008 Polaris Sportsman 400 HO. This quad runs great, but when I turn the lights on it dies. No night riding for me.

 

Welcome to the forum. Open the headlight pod and check the connector going to the bulb. This is one area shorts can happen on wiring because of all the bends and twisting. May be a frayed or bare wire grounding out.

 

Thanks old polaris tech, I will check out and let you know...

 

I checked the area you mentioned and there is no frayed or bare wires. So, i removed the front storage compartment, which was difficult to figure out at first, to access the wiring behind it, still no bare or frayed wires. I started the beast and flipped the headlightt switch on and it continued to run. I did find an orange with white stripe and a black wire coming out of the harness that wasn't attached to anything. They have a spade connection with heat shrink on them. Any thoughts?

 

The two wires are spares,not used. The orange/white(actually red/white) is hot with the key on and is an auxiliary wire used for adding accessories. If it runs ok since you pulled the storage compartment you probably had a pinched wire.Look close for any signs of this and make sure all wiring is free and clear when you put the box back on.

 

Well, I said I took the front covering off to check wiring harness. When I said I started it with headlight switch on and it run fine, that was without headlights connected. When Iattached the headlights to their connectors the beast died after about 10 seconds. I have used meter on light wiring and no shorts are indicated. Got a question since I am new to these Polaris quads...
My dirt bikes and Harley will still run with battery disconnected. When I started the beast and disconnected the battery it died, and would not pull start. Is this normal?

 

Don't disconnect the battery when the machine is running or you can have more problems than just the lights! You take a chance on damaging the regulator and cdi. If you hook the lights back up and it dies you still gave a short somewhere.It may not be in the wiring,but could also be in the switch itself. Here's a 5 buck manual that can help you trace down the problem.2008 Polaris Sportsman 400 H.O. Service Manual PDF Download

 

My problem may have been located, but I want to see if I am right. I decided to run thing with only one headlight, ran for a while, switched to other headlight, samething. Checked stator, no shorts, checked output and it was 50 at idle and increased with rpm. Checked rectifier again, shows 14.56 going to battery, which is good. However, I decided to pull rectifier off and check diodes. The negative side has no reading at all and unless something has changed over the years I should be getting reading here. I also got a 21 volt AC eading in system at idle. My guess is rectifier is capable of charging battery, but can't handle the access when lights are turned on. What you think?

 

Load test the battery before you replace anything. The charging system shows good,but if the battery has an open cell it may not be able to handle the voltage from the regulator.A battery can charge up to 12 volts or more,but can still fail a load test. Eliminate the battery as a problem and go from there.

 

Welcome to the forums.