Light Switch on a 140 versus a cub

[cchatham]

We're trying to replace wire on a 140 that had had a short somewhere on it. Basically, taking 14, 12 and 10 ga wire and running it as it was.

We've made the general assumption that the wire that was on it wasn't bassackwards or wrong. We're also assuming that things will be somehwat similar to the cub we have, more or less as a reference. We know it is a 6v positive ground system.

For those of you who've been into the wiring on Cubs, here's what our problem is.

The light switch has 4 settings 0, 1, 2 and 3. 0 kills everything. Can't find what 1 does. 2 turns on the front lights, and 3 we can't tell what it does. Trying to rule out a bad switch, in case anyone knows how to tell if it's good or bad. If there's a replacement switch (reasonably priced) then that's plan B. Would prefer to make what we have work.

Can't remember what the cub has on it's switch, but was hoping that they're similar, and wanted to ask someone here who'd possibly worked on their cub's electric system and found out what switch positions did what on the two tractors.

Any help appreciated.

We found some info on some other Farmall tractors, but they're not for the 140, or are just "general" diagrams.

Sc

[Rudi]

Carl:

On the Cub Manual Server, there is the Preventive Maintenace Manual, which applies to the Cub, Cub Lo-Boy, 140, 240, and 340 Series Tractors. On Page 28 to Page 32, can be found a bunch of info on the Starting and Lighting Equipment.

I hope this helps.

I also just recently acquired a I&T publication called the Light Utility Tractor Service Manual which covers the 140. I can peruse and see if there is anything of use to you in it, if so, I could then scan and send you the relevant pages. Might take a day or so, but I am willing.

Let me know..

[Bigdog]

The 4 position switches used on the early model cubs were used with a cut-out rather than a voltage regulator. First position was low charge, second position was high charge, third position was dim lights and fourth position was bright lights. Never had a 140 but I would think it was late enough that a voltage regulator would be standard and if a 4 position switch was standard the positions would have different functions. Possibly Off, Dim Bright and Red (rear)?

[Jim Becker]

As Big Dog conjectured, the early 140 (introduced in'58 ) would have electricals that are essentially identical to the '58+ style Cub. Light switch positions were (O D B R).

[cchatham]

Cannot figure this thing out at all.

Rear light tests okay. Probe on the wires going to the wire shows I'm getting 6v to it.

I take the light off, hook a charger to the bolt and to the wire, and both the red & white lights light up fine.

Can't get the light to work on the switch, so I take it off the terminal it was on and piggyback it on the one where the front lights are at. Figure that if the front lights light, then the back one would. No deal.

And, I've done the simple thing, like flipping the switch on the light to each of the 3 positions on it, so I'm not trying to power a light that's off.

Pulled the wire coming out of the light, and get 6v at that point, and have taken the light off and plugged it in to a charger and can get the light on when the + is hooked to the bolt, and the - to the wire.

Any ideas as to what to try next?

This ought to be simple to figure out, unless I've got a bad wire that tests good.

[Bigdog]

Check the ground for the light at the tractor. Since you can get the light to work off the tractor and you can measure 6 volts at the lead to the light, it only leaves the ground connection which is the mounting bolt. You need to assure that the mounting surface is clean and shiney on both the light and the tractor. If it is a fresh paint job, the paint is insulating the connection. You could add a bonding washer to the mounting bolt to help assure a good connection. The other thing you can do is to add an external ground wire to the light and assure that it makes good contact at both points of termination.

[Matt Kirsch]

Sounds like a ground issue to me too. As I recall, some of those lights were set up with springy "scratchers" on the ground terminal of the light bulb. These would contact the inside of of the light housing and make a ground. When the inside of the housing gets rusty, and/or the scratcher falls off, you lose your ground.