Coil kill wire harness problem.

M0michael84

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Briggs 23. Ok after chasing what i thought was a fuel problem i was getting no spark on my left coil. New plugs still no spark. Swapped coils and still no spark on left side. The coil i moved over to the right worked fine. If i remove both kill wires from coils engine runs like a champ. Put them on only one side gets fire. I had to get my grass cut today so i rigged two separate wires one coming off each coil. Heres the weird part. When i touch these two wires together and NO other ground it will kill the engine. Im not really an expert on this kill system but it seems somehow its finding a ground somewhere. Its on a 2007 john deere z425. All other safety switches are functioning as they should. I cut 2 acres today no problem. Just had to use my two wires rigged to kill it.
 

bertsmobile1

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There is a diode that does between the kill wire to prevent the coils talking to each other.
So you will need a replacement sub harness ( easy way ) or make your own .
If you search this forum using the words COIL DIODE you should bring up a few posts that have either the part number or the value of the diode required.
I just replace the section of the loom which from memory has the kill wires and the carb solenoid on it ,
 

emberto1946

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New to this forum so please be gentle with me if I am posting in wrong section. Currently 'locked down' in France (Covid-19) so away from my UK base and struggling with a Countax C600H ride-on fitted with Briggs 16hp Vanguard engine. To cut an extremely long story short I bought this mower s/h about 2 years ago and it had been built, I think, from several different 'donor' mowers. However, it wouldn't start on the key so I bought a new ignition switch. Still no joy, only started when shorting out solenoid so did that for a while then about a month ago I decided I should get to the bottom of this. This mower has safety switches for the safety switches and a printed circuit board for the ignition circuit. After lots of different attempts I decided to disconnect all the loom including the pcb and just wire up the engine as though it was in a go-cart or something. It now spins over like a good-un but won't fire. I've connected the fuel solenoid to the spare terminal on the ignition switch and that works. I've disconnected the 'kill wire' loom as the diodes are visible so they may have burnt out, still no good. Found that one plug lead had been chewed by a mouse (found the corpse by the flywheel) but only the outer insulation. Getting a spark, left or right but never at the same time and never reliably - i.e. sometimes one will spark but not the other and vice versa. Also, the plugs are always dry. New fuel filter fitted, cleaned out carb bowl (which was full of fuel) and am now at my wits end. The grass is growing, I have arthritis and cutting half of the grass with a push along petrol mower has put me on my back for two days! Can anyone help please? The ignition switch has M, S, B, L and G terminals. I have connected M to the charge wire coming from the magneto. B to the battery, S to the starter solenoid and L to the fuel solenoid.
 

emberto1946

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Sorry - should have said that I replaced solenoid as well.
 

StarTech

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If the diodes are toast then it is very possible 12vdc have been fed into the coils which destroys the electronics in them.

I see many wiring diagrams indicating the diodes installed backwards in my opinion and won't block the +12 vdc. This is because these coils by design should only be grounded.
 
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