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Discussion Starter #1
I have a 99 Kodiak 400. The negative on my winch touch the frame and toasted several ground wires. I have replaced all the bad wires that I've found. It still won't start I have good spark. I think the diode is bad. I checked the volts on it. 12v going in and 0 coming out. So is this probably the reason it won't start? Also if it is the diode where would be the best place to pick one up?
 

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Diode?
I'm not clear which component you are talking about?

A diode is an electronic component that acts as a one-way gate for electricity. Most are mounted on circuit boards and are light duty -heavier ones are found in bridge rectifiers for converting AC to DC power and some other applications. Your regulator/rectifier definitely has some and your CDI box probably has some inside.

Are you talking about the regulator/rectifier?
 

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Discussion Starter #3 (Edited)
No this one looks similar to a fuse. It was wrapped with electrical tape located in the wiring harness. I looked online to see how to text it and there is no voltage drop in between it. 12.4 on the positive side and 12.4 on the neg side. When I put the leads from my tester on it, set on diode it reads the opposite of what it is suppose to. Red lead from tester to the side that is marked positive and the black lead to the other it reads l. If I reverse the leads it reads 502. From what I found on the internet I should get the 502 reading from the + to the - not l.
I called it a diode, that's how listed listed on my manual. It looks like it is also called a rectifier.
 

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Discussion Starter #5
Ok I was wrong about the voltage not coming out. I just checked the socket that the diode plugs into and it has 12v on both sides of the plug when you turn the key on. I guess I don't understand what the diode does. I would think that you would only have 12v on one side of the plug and when you put the diode in the plug it would complete the circuit and flow of current.
 

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Hey..car you are correct it is a diode. Newer machine have tow to three of them The diode should test with voltage one way and none the other same with ohms. Diodes sometimes fry open meaning the will read backwards. Diodes usually are in charging and switching circuits. Some machines have a diode in the brake light circuit if the brake switch isn't closed the starter will not turn over on others there is also a diode in in the neutral switching circuit. I don't have a manual for your machine so I'm not sure of its function. They are cheap so you could replace it. But it sounds like your machine is turning over but not starting?
I'm stumped about the "negative" touching the frame the winch and the frame and the battery share the same ground?
Back to not starting how did you test the "spark" If you know you have spark and it won't start. Put in a "new "spark plug first. A weak plug will sometimes not fire under compression.

Good Luck!!
 

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Ok I was wrong about the voltage not coming out. I just checked the socket that the diode plugs into and it has 12v on both sides of the plug when you turn the key on. I guess I don't understand what the diode does. I would think that you would only have 12v on one side of the plug and when you put the diode in the plug it would complete the circuit and flow of current.
12 volts to ground from each side?
The diode is a one way gate. If there is a possibility of voltage in either direction it will limit it to one direction.
 

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Hey..car you are correct it is a diode.
I stand corrected.
Thanks reogem!

I do see a diode in your 99 Kodiak electrical schematics part #3WP-81980-00-00. They are about $7.
 

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...
I'm stumped about the "negative" touching the frame the winch and the frame and the battery share the same ground?
Back to not starting how did you test the "spark" If you know you have spark and it won't start. Put in a "new "spark plug first. A weak plug will sometimes not fire under compression.

Good Luck!!
:devil:
 

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It is a diode...

Ok, So first off it does have a diode in part of the start circuit.

My 93 Kodiak 400 had the fan control disconnected when I bought it, and when I was going through the test steps the fan worked fine. When I jumped the temp sensor pin on the fan control connection the fan came on just like it should, but the starter also came on. I was stumped by this.

So I got to digging through the wiring diagram and this is what I have found out.
When you start the engine, the starter button grounds out both the starter relay and the oil temp light. That way you can verify the light works. The diode is between the oil temp light and the starter switch.

If however your fan motor control were to ground out that same wire to turn on the oil temp light it would also engage the starter. So the diode is there to prevent the starter relay from going backwards and grounding through the control.

So now I know my diode is either bad or maybe removed during a re-wire at some point.

Now the question is where is this diode supposed to be located. I haven't actually looked for it yet, but if anyone knows off the top of their head I would greatly appreciate it.

Thanks
 

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The diode should be underneath the seat. There will be a bunch of small electrical pieces and wiring in the area.

Go to any online yamaha parts website. Once on your specific ATV model, go to "electrical 1" diagram. Item #41 is the diode. It will show you an approximate location on the bike.

Diode part #:
3WP-81980-00-00
 
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