1440 Vanguard - no spark after electrical fire at ignition switch

[Edward]

I was mowing a few weeks ago and the mower wasn't running right, then the PTO light came on, then I noticed smoke, then flames coming from the back of the ignition switch.

I ordered a new ignition switch and have been testing/replacing the wires one-by-one. Now I can get the starter to fire, but I don't have spark on either side (I have those inline spark testers).

I have unplugged the yellow wire that grounds the magneto (on the right side of the engine), and it still doesn't spark on either side.

I tried starting it by directly connecting the starter to battery +. Still no spark with or without yellow kill wire on the side of the engine unplugged.

So does this sound like a kill wire/diode problem? Or maybe the coils are bad? Or maybe there is a bad ground somewhere?

If it is the magnetos/kill wires - is there an easy way to get that engine shroud off? From my research it appears I will have to remove some bolts and shift the engine forward. One gentleman used an engine hoist, but I don’t have one.

Anyway, any insights or tips would be greatly appreciated.

[R Bedell]

First, welcome to OCC..........

I ordered a new ignition switch

Was the switch you install a Cub Cadet #925-3163 Ignition Switch ??

With that melted wire mess, was the wires (once cut and trimmed) installed on the correct switch terminals ??

I have unplugged the yellow wire that grounds the magneto

With a DVM (meter) did you check to see if this yellow wire is shorted to chassis ground ??

So does this sound like a kill wire/diode problem? Or maybe the coils are bad?

IF....the yellow wire is not shorted to chassis ground, then I would suspect the Ignition Coil(s) are bad (shorted or open).

I have NO experience with the B&S Engines in this arena, but with the Kohlers one has to remove the engine from the tractor to gain access to the coil.

My suggestion before anything else, is check the Yellow (Kill Wire) to see if it shorted to ground.

[Edward]

Thanks. According to my multimeter, that yellow wire is only grounded when the ignition switch is on off.

This is the new ignition switch: The ROP Shop Compatible Ignition Switch with 2 Keys Replacement for Cub Cadet MTD 725-3163 725-3163A 725-3163P 925-3163 https://www.amazon.com/dp/B073HL42FT...roduct_details

unfortunately, it's looking more and more like something with the magnetos as you suggest.

Part of me suspects the brake pedal safety switch or the seat switch. It will be the weekend before I can really get in there.

Thanks again for looking at it. This is how one learns things, right?

[Edward]

Update: I replaced both coils and the kill wire with the diodes in it. Now my spark testers show spark on both sides, and it's running fine.

I was able to get to the coils without unbolting the engine from the frame. I unbolted various pieces around the shroud on the back of the engine and eventually got the shroud out enough to where I could get to the coils.

Thanks again for the tips!