H light box

Is there replacement parts for the dimming resistor and field resistor or more modern parts to replace them?
I have these labeled as to Bob M's diagrams, are they correct?
Dose the rear light come on when the lights are on, I don't have a switch on the rear light.
Does the lead from the ammeter go to the starter or the starter push button switch?

Randy

Looks like you have everything labeled correctly. On my H the negative side of the ammeter just went to the push button switch not all the way to the starter. My rear light comes on in both the dim and bright light settings. I do not know if new replacement resistors are available or not. Mine looked about like yours but they seem to work.

Your questions in order:

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I highly doubt "correct" replacement resistors are available.

My recommendation is to get rid of the field resistor entirely then replace the original cutout relay with a voltage regulator. You will find the battery will stay up better and will enjoy a longer life with a voltage regulator.

Looks like your headlight dimming resistor coil can be straightened out and reused. Just make sure not to breathe any of the deteriorating insulation (it's probably asbestos!), and that the resistor coil does not contact any other wiring or grounded metal after the box cover is reinstalled.

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Your wiring labelling looks correct. The only exception may be the ammeter connections. Depending on your tractor's ground polarity the ammeter may "read backward" if connected as shown. If it does simply swap the wires at the two ammeter posts and it will read correctly.

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No separate switch is required for the rear light. The #2 terminal will cause it to burn bright with the switch in both the D and B settings.

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The ammeter must connect to the "hot" side of the starter switch.

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Nice photo BTW(!)

Great photo. Would you give us some pointers on the equipment, settings, lighting to do that?
I've cleaned up three light boxes like that, replaced just the fuse, did a little straightening and all the functions worked great.

Gordo

Nothing fancy Gordo, just a Canon digital camera. The key is using the macro settings on any digital camera to get these kinds of closeups.
I try not to use flash if I can get away with it, just hold the camera as steady as you can. My shop lights are pretty bright so I can take most of my pics without flash :wink:

Randy

Thanks for the detailed answers guy's!!
The wiring & decals will finish up this 43H!!

Bob, feel free to use any pics from my website, If you want the original without the text let me know and I can send it your way.

Randy

Randy - With your permission I'll add this image to my online wiring diagram page. It looks good exactly "as is" - no need to change a thing(!)

Thanks! Bob M

Permission granted.

Randy

Randy,
Agree with Bob M about the voltage regulator. Your battery will love you, no more over or under cahrging as with a cutout. They make them with a curved bracket to fit on top of the genny out of sight. Tho "correct police" will never know!
As for the dimmer coil, I would jumper the terminals it connects to and be done with it. Don't know why the put dim and bright on these old girls. Dim was about like two matches and bright was about like two candles. Drove a many hour with em at night though

You got that right Randy! The IHC designers should properly labelled the two headlight positions Dim and Dimmer. Or maybe Dim and REALLY Dim...

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Anyway as a kid I too spent many hours running M’s in the dark: Fitting in the spring and pulling beans in the fall. The combination of dark soil and weak lights severely taxed even young teenager’s eyes!

Incidentally the heavy tillage tractors we use now all have 6 halogen floods facing front, 1 to each side and 4 more out back. Compared to the old M’s lighting it’s like working the field at a Monday Night Football game(!)

After I put in my alternator, I redid the wiring and put 4 Piper Cub landing lights from NAPA (one high pair for snow plowing) on my 1966 140. it's a whole new world at night.