IH 300U wiring....last question I hope.

[Dave H (MI)]

So the 450 schematic was helpful in general but different from the 300u. For example...I have a key switch not an on/off switch and a push button. So I did a continuity check on all wires. Keep in mind that, as strange as a connection looks, the tractor ran in the condition it is in with the exception of those wires marked unconnected. I only removed the starter and battery and these are the only changes (in the back half wiring) since it last ran.

The ammeter has a red and a white wire built into it which are attached to the two posts. Attached to the red wire post is a wire which reads continuity to the coil positive side. No wires go to the key switch. The wire on the white post is unconnected, but shows continuity to the red post.

The key switch has a center post and three outer posts. The center post is unconnected. One of the outer posts is unconnected. A second outer post connects to the light switch AND shows continuity to the coil positive side ( it is spliced into the red wire from the ammeter). The last outer post is connected to the alternator side connection.

On the starter switch there is always continuity from center post to the light switch/coil lug. There is continuity to the other two lugs only when the switch is turned on with the key.

The starter solenoid has three posts. One goes to the starter. One is attached to the battery and the center one (activates solenoid) and no wires are connected there at present.

Anything here ring any bells? I just need a push on where those unconnected wires need to go. All else is good I think. Thanks and sorry for the length on this.

 

[used red MN]

It almost sounds like you intended to post a picture with this description. If not in my mind there is a lot of difficulty with giving you very accurate help. While you testing this continuity where was the positive battery cable terminal? If it was unhooked and laying against a metal part of the tractor your readings are worthless because the points were probably closed providing continuity to the engine block. And if the cable is touching metal everything is one big circuit.
Does your switch look like the one in the first link? If so clean yours off and find the markings on it. Looks like the middle should be the start terminal. You need to forget that it ran the way it was and wire it correctly and move on with a happy life. If you do not you a relying on the work of some other backyard genius who has incorporated a lot of problems into your machine. I am sorry if that was you but I think it was running as it was when you bought it. The second link is to your last post that shows your ignition switch and not very well I might add. I understand about short wires and not being able to pull it out very far.
Example ignition switch

Other post

 

[Janicholson]

Best of my thinking. Contenuity is not connectivity. Nor is it a sure delivery of voltage or ground. SO here goes.
The ignition switch has 4 connections. I believe the center connection is battery. If clean, it should have BAT lable made into the plastic at the terminal. That should be connected to the ammeter on the side not connected to the starter relay.
There should be an IGN terminal that should go to the coil through the resistor if 12v, or directly if 6v.
There should be an ACC terminal it can be ignored for this discussion.
The third should be an S terminal it should connect to the S small terminal in the starter relay.
This should allow voltage to start at the battery, go to the starter relay big terminal not connected to the starter motor. Then go (at that terminal) up into the dash with a #10 wire and connect to the Ammeter (alone no other wires on that terminal)
from the opposite (load) side of the ammeter a thick #10 wire should go to the voltage regulator Bat terminal.
another wire from the Load terminal on the ammeter should go to the fuse, and from there to the light switch.
Another wire should go from the ammeter load side to the Bat terminal of the ignition key.
The key shouls show battery voltage at the bat terminal all the time.
The ign terminal should show battery voltage when the switch is in the run position and if the switch is in the Start position.
The S terminal should only show volts when the key is turned to the Start position, no other time.
Jim

 

[True Son]

Janicholson.your advice on my Super C 12 Volt conversion was spot on!
The volt meter reads correctly now! Thanks much, Cmore

 

[Janicholson]

Thanks, I can just see these tractors in my head while resting up for the next project. Jim

 

[Dave H (MI)]

Hi Jim. I will clean and check for markings on that switch. It is hard to get at. The #10 wire to the ammeter is not going to work. The gauge has very small lugs and they are close together. That and it DOES have other wires that go to the lugs that are integral to the gauge. Not sure what they do but they are there. The tractor has no voltage regulator.

 

[Dave H (MI)]

Actually, I meant to take a picture of the starter solenoid but ended up thinking it was not necessary. The battery positive is on the bottom large lug of the solenoid. The top large lug is connected to the starter. The center small lug is currently not connected. I wouldn't leave the battery shorted out to the frame. That would get pretty toasty, lol.

The starter switch in the link is just like the one on the tractor. There are two wires on it that are not connected so if I clean it up tomorrow I may be able to read them, maybe. The last loose wire is to the ammeter and I will just have to sort that out best I can I guess. I do want to fix any errors in the wiring, but more than anything else I would like to find out if this tractor is going to start with minor adjustments or if it needs to go down the road. So before I spend time on rewiring, it seems that I should not fix what wasn't broken and get to the main purpose. This tractor pulled my boom sprayer in small fields for many years before the rear main gave up the ghost. I'm pretty certain that it is wired correctly for the most part. But I am not the one who inflicted the restoration on this one. Reading my post it is almost as good as pictures. It describes every wire and where it goes and then ends with a wire or two that goes nowhere. Process of elimination. Identify what you know and whatever is left has to be....

I will let you know what I find. Thanks for the help. You have been great.

 

[Janicholson]

Some (non-original) gauges have wires going across the terminals from one side to the other. these (if original)are called shunts. They provide the tiny known resistance that is used to drive the meter works. The OEM meter has a shunt internal to the meter. The terminals shown in this advertisement is easily wired as I described. If what you have is a replacement meter that has wires interconnecting smaller or closer terminals, I recommend using the correct gauge. Jim
The original OEM meter

 

[used red MN]

Apparently a photo was not meant to be. Just to double check Is this an AMMETER that shows discharge and charge?? Or a VOLTMETER that gives a voltage reading? The connections on it seem weird to me if it is an ammeter. The built in wires are probably an internal light, which connected as you are saying would not power the light. I have seen volt meters that have small leads coming out of them like that to make the connections to read the voltage. A voltmeter will not carry a load across its terminals as an ammeter would. It would still show some level of continuity across its feed wires. A volt meter needs to be wired differently than an ammeter.
If you have an ammeter or really either way it sounds like the ..white.. wire on the ammeter at the end of your second paragraph that you say is disconnected, is probably the feed that should go on the starter terminal with the positive battery cable.
I am sorry if I am coming across with a grumpy tone. I just think there is a good possibility that you unhooked more wiring back when you took it apart then you are remembering.

 

[Dave H (MI)]

Good morning! A couple things. While some memories are lost, others are clear. You can safely rely on my statement that I only disconnected those wires that attached to the battery and starter. I can post any pictures that will help today. The tractor is in a building 20 miles from here. I couldn't get photos last night. Anything you especially want to see just let me know.

 

[used red MN]

Sorry if I was making unwarranted statements. Just verifying that it is an ammeter would be good for now. Just the fact that you say a 10 gauge wire cannot be placed on your gauge is difficult for me to understand. I have a spare universal automotive ammeter from NAPA here in my garage. Looking at it confirms that 10-32 studs come out of the back which I believe is the common size. Terminal ends for number 10 screws that are for 10 gauge wire are very common. So still trying to figure out your statement about how it will not work. Also originally the ammeter would have the main mounting studs double as the connection lugs. They simply have insulating bushings on the U bracket that clamps it in the dash. Looking around a bit on the net for oddball gauges I did find this one I have attached that has a separate set of stud terminals for the connections. Is your ammeter like that one? If so that may partly explain the difficulty to make connections to it.
Example oddball gauge

 

[tperson]

Dave - PM me and I'll send you a copy of the operators manual

Edit: crap, forgot YT doesn't do PM's. Let me figure out another way for us to email each other without posting our address for the spammers to see.

This post was edited by tperson on 07/28/2023 at 08:07 am.

 

[Dave H (MI)]

Well most people find me without much
trouble. Start with hagecpa. And then
remember that Americans Only Like (dot) Corny
Old Movies. That one even gets by ebay
filters, lol, and thanks much!

 

[Dave H (MI)]

So...don't worry about unwarranted statements. No such thing. I just want to make sure it is clear that only the battery and starter were disconnected by on the rear half of the tractor. I will rewire/check all the connections as needed later BUT...the tractor ran as wired before service. A problem on forums...all forums...is that after a while we lose focus. The prize here is the engine starting. Gauges are unnecessary and are all hooked up as when I bought it. I have plenty of time. We can rewire it later if needed. Three wires, if I remember correctly. Figure out where they go and I can hear it crank after ??? years. Gonna post a bunch of pics in a new thread for you. Thanks...more than I can say!

 

[tperson]

(quoted from post at 08:41:00 07/28/23) Well most people find me without much
trouble. Start with hagecpa. And then
remember that Americans Only Like (dot) Corny
Old Movies. That one even gets by ebay
filters, lol, and thanks much!

Sent...I hope