MF50 ignition switch

[EricG1793]

I'm wondering how the ignition switch is supposed to work on an MF50.... Ours came with a Bombardier (go figure) 3-way + start switch, which I thought was overkill. It has a dedicated starter button and an aftermarket light system with its own switch mounted beneath the starter switch. I figured that all the key switch did was cut power to the starter and coils, so a two-way (on/off) switch would be fine.... I saw a stock switch at Tractor Supply a couple days ago and thought it only had two terminals on the back, but I was wrong... looking online, it's three.

I noticed that, on the existing switch, one wire comes from the top of the solenoid to provide power to the switch at one post. Another post leads up to the ammeter (the other side of that goes to the voltage regulator). One post has two wires: one going to the start switch, one going to the ignition coil.

Given the fact that the switch is connected to the ammeter, we checked for continuity in the ammeter and it's OK.

In using the existing switch, only the first position after the off position will provide power. The second one does nothing, the starting one does nothing.

I know nothing about electrical systems, but it seems kinda strange to me how it's set up. A point in the right direction would be greatly appreciated!

 

[trac]

On mine the first click of the key is power than
push the start button, the second click of key is
the lights. Go to Ferguson Enthusiasts org. look
under resources or restoration all the elec. will be
there.

 

[Aaron Ford]

The factory ignition switch should have three wires and four detents. Terminals are hot, run and lights. The detents are off, run/no light, run/light, and no run/lights. Wire your coil and starter pushbutton off the run terminal. You could use inline fuses, but I used a small fuse block and a pushbutton circuit breaker for protection. Oh, switch on right, pushbutton on left.

Aaron

 

[EricG1793]

Is the hot terminal the terminal that the switch gets its power from (the battery)?

I take it the ammeter should not be connected to to the switch? If not, how should it be?

That diagram on fergusontractors is helpful. It indicates that, in short, a wire comes from the battery side of the solenoid, passes through the ammeter, and to the voltage regulator. Another terminal comes out of the voltage regulator and to the ignition switch.

Currently, a wire goes from the battery side of the solenoid to the ignition switch, and another one goes from the ignition switch to the ammeter to the voltage regulator.

Unless the parts diagram is totally wrong and/or I'm misunderstanding things, this tractor is totally wrong. It DID run this way, but it sat for a couple years and something went wrong; now I'm having the no spark issue (not getting reliable voltage at the coil as I mentioned in another thread). I guess the next step is to replace the switch and get the wires configured the right way.

Thanks for the pointers, guys!

 

[trac]

Sounds like your on the right path the + side of
coil it's not getting power? If not the first thing
i would look at since the tractor sat awhile is
rusty / poor connections clean everything loosen &
and retighten all contact points that will help.

 

[EricG1793]

Yup, put on new battery cables and terminals and loosened/cleaned all connections with a wire brush... it cranks very well. Although, come to think of it, we've never once looked at the generator cables. I don't understand how they could pose an issue with the coil, but for all I know, they could.

 

[Dan S (NY)]

Watch out for new switches, make sure it feels tight and not sloppy when you turn it. See the link below for what happened to mine. No fuses in the original wiring diagrams, but I will be installing some inline fuses in all my tractors from now on!

Dan
Crispy switch

 

[EricG1793]

Yikes, that's scary! I'll be sure to find a good one. Thanks for pointing that out.

 

[EricG1793]

I rewired it using this diagram:

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=mf&th=92333%3E

The switch continues to be finicky for starting, but stays running. We'll replace it. Hopefully with a normal 3-way switch that we'll use to actually wire up the lights the way they're supposed to be.... They current have a rocker switch screwed into the paneling below the starter switch and they draw their own power from the battery (well, they would if I hooked them back up).

All seems to be pretty well otherwise. The ammeter shows a draw when cranking. However, once it starts, it goes ballistic and rapidly shoots back and forth, occasionally settling down for an instant to show that it is charging. I assume this isn't normal?