# chainsaw kill switch/circuitry problem



## vbr666

how does kill circuit work and what can be wrong if the chainsaw is working fine, except, you can't kill the engine on the switch, but only by choking it with closed airflow (butterfly) valve?

it's mcculloch 835AV.


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## billsmowers

the kill switch works by shorting out the coil to ground if the switch is not working then you may have a broken wire,defective switch or kill wire may be diconected at the coil

hope this helps

bill


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## vbr666

the wires have been replaced.
the switch and it's contacts are undamaged.

so there's the coil left.
what can i do about it?
how is it connected to the casing and the rest of the engine, is there any contact at all or just few screws?

if I remember correctly, I've seen 2 contacts coming out of it, to which wires to kill switch are connected and there is a spark plug cable. that's it, and 2 screws to the casing.

I couldn't find replacement parts for that chainsaw online, at least not the coil.
Is there a way to reconnect contacts to coil and how is it possible that coil is not connected to contacts if it's working correctly because the chainsaw itself is working?


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## billsmowers

the kill wire to the coil is a pust on conection. you say you have replaced the wires + switch have you grounded one side of the switch to the engine? the other side go's to the coil kill conection

bill


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## vbr666

hello again.
after a while of working with my saw, I've returned back to the garage table to try to see why the kill switch isn't working again.

I recorded this video so you could see all connections, but without wires which I removed for testing:
View My Video

can you tell me what could be wrong if both wires, which have been connected to marked connections on video, are working fine (I've tested them today) and if each connection was firm, not loose, including the red switch button itself? As I said I worked with my chainsaw since last time I posted message here and the spark plug is working fine. As you see in video, spark plug cable is connected to same coil as the kill switch, but unlike kill switch, spark plug is working fine.

The switch is grounded like it was with it's original wires which have not been touched since I've bought the chainsaw and until my last message here where I've said that wires have been replaced.

edit:
here, I've removed the coil completely and cleaned it up, so tell me if there's anything to do about it or if you see something what might be the reason for it's partial failure:
http://www.sendspace.com/file/wvj8rk


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## ftfixer

*kill switch*

make sure that the connectors on the coil are clean and free of corrosion its kinda like a vehicle battery to much corrosion and it will not make good contact. even though the wires were replaced you may not have a good ground looks kinda rough at the coil.:dude:


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## smoker

About half way through your video showing the back side of the on/off switch, it's difficult to see if the two tabs of the switch touch together when the switch is in the OFF position.

If you have an ohmmeter, check to see that it measures zero ohms or almost zero ohms when the switch is off.

An alternative test is to idle the engine , then short the two wires going to the switch with a jumper wire or a pair of long nose pliers.It should shut down.


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## bec98x

sounds like you have done your homework and thought things through.

I have replaced 2 coils this week that would not turn off and after testing all connections and bypassing kill switch (by touching the kill wire directly to the engine block) I replaced the coil and all is good.

Moral of the story is they do go bad.


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## vbr666

hello again guys.
there is no corrosion problems, all contacts are almost pefectly clean.
wires are relatively new, no problem with them, I've tested them to see if the 'juice' goes through and it does.

also, you don't have to worry about the red kill button contacts, they do touch each other, but not on the video because I unscrewed its screws to remove the wires. once the screws are back in their place, the contacts are firm.

bec98x, do you know where I could buy the coil and how much does it cost?

I've been looking for it online but unsuccessfully, only found one (or two) on ebay, but that was too pricy, about 50$ with shipping costs to Croatia if I remember well...

any further advice is much appreciated, so are the last ones.


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## bec98x

I am not sure, I do not buy any parts for those things.


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