IH 424 Wiring question

[GeorgiaDave]

I'm getting ready to re-wire my 64' IH 424 (gas) tractor due to multiple issues. I have a shop manual, but the wiring diagram shows a few thing that has me a bit confused. The areas on the image circled in red show what I'm confused about.

If anyone has some thoughts, I'd sincerely appreciate it!

I would have liked to keep the original wiring, but it's been patched a hundred times, and the insulation has worn off in many places shorting the harness. I added a neutral disconnect in an effort to maintain the battery - killed one last year with a short that I didn't catch.

Thanks in advance !!!

 

[Tim in New York]

Good luck! The wiring on my 2424 is a mess - I am just satisfied that it works somehow. In the upper right hand corner of your diagram, I think one of those circled lights goes in the back of the tachometer, and the other is a peanut light that sticks out under the little shelf on the back of the hood, lighting the instrument panel. OR, one is a peanut light bulb that sticks up out pf the panel itself. I think my tractor has all 3 -- not working of course!
Tim

 

[soupkid]

I'm guessing the the 2 circles on the right side connect to each other (same symbol).
The big circle on the bottom looks like a diode of some kind and the far left looks like a connector.
Is there a legend somewhere in the manual ?

 

[GeorgiaDave]

I assumed that this diagram did not include any lighting - there's no lighting switch, headlights or taillights shown at all. But, it's an odd diagram - shows the Ammeter, shows the Oil Pressure gauge, but doesn't show the Tach!

No legend at all in the manual for the 424 (I have the I&T shop service manual, was unable to locate anything else). I can't imagine the need for a diode on the coil resistor - it's just there to limit current during normal operation (the .natural' wire bypasses the resistor on startup), and a similar image to that can be seen in the 'multiple connector'.

 

[soupkid]

Might be a reverse current diode

I assumed that this diagram did not include any lighting - there's no lighting switch, headlights or taillights shown at all. But, it's an odd diagram - shows the Ammeter, shows the Oil Pressure gauge, but doesn't show the Tach!

No legend at all in the manual for the 424 (I have the I&T shop service manual, was unable to locate anything else). I can't imagine the need for a diode on the coil resistor - it's just there to limit current during normal operation (the .natural' wire bypasses the resistor on startup), and a similar image to that can be seen in the 'multiple connector'.

 

[GeorgiaDave]

Maybe acting at a TVS diode? I'd say it's definitely a possibility.

I'm considering replacing the coil with one that has a built-in resistor, that would simplify things a bit.

 

[Jim Becker]

My best guesses: The three identical symbols that look like a wire taped back to itself represent wires taped back to themselves (unused taps for some optional attachments). Since no lighting is shown, the rectangle on the left may represent a connector to feed the light switch. It appears to be an always-hot connection. Does the carburetor have an electrical control, like for the idle speed? If so the remaining mystery circle may be at the carburetor. It appears to be powered with the ignition. If repro harnesses are available for this model, you might consider buying one. It maty cost less than buying all the wire and connectors that are required and be a simple plug and play installation.

 

[Jim.ME]

I agree with Jim Becker on the turned back wires and other connections.

I don't see a diode anywhere on that diagram. The only reason a diode would be added, on switch side of the resistor, is if someone converted the generator to an alternator and pulled power from that point instead of running a separate wire from the switch; you have not said you have an alternator instead of the generator. If you have an alternator several things will need to change around the charging system.

If you have a mechanical tach, it will not show on a wiring diagram unless it has a backlight and it appears there are no lights shown on this diagram. Is your tach mechanical or electric.

A current true 12-volt coil has the proper size wires and number of windings of said wires to provide the required resistance; there is no internal resistor inside the coil. The use of the 6-volt coil and resistor was to allow provide full voltage to the coil when the starter was engaged (the wire between the coil and R terminal of the starter solenoid).

 

[used red MN]

I'm considering replacing the coil with one that has a built-in resistor, that would simplify things a bit.

In my opinion if you did that you are doing away with a good feature. Right now when cranking to start the 6 volt coil is being fed 12 volts for a hotter spark. Using a 12 volt coil eliminates that feature. Not something I would suggest. This may be a bit of an echo of the last part of Jim’s reply 8.

 

[GeorgiaDave]

Jim and Jim - the idea of a turned back wire seems correct to me. I noticed a few wires on the existing harness that went nowhere, that is probably exactly what those designate.

I replaced the original alternator a long time ago with a 1-wire alternator, so no need for the regulator. It outputs directly to the battery +. All the gauges on the dash have backlights, including the tach, but the tach itself is mechanical. In my manual, which covers quite a few models, there are wiring diagrams showing the headlights and dash lights, but for the '414' model, and the wiring diagram, which I just noticed for the 414, does not show anything 'other' than the lighting system. Kind of odd. Most likely it's just a missed section, hard to say, but no explanation in the manual.

I did find a break in the wiring, which I'm going to patch to get back to work, I'll look around for a repro harness, that's not a bad idea at all, thanks for that suggestion. If I can't find one, I think I'll live with a patch for now, and re-wire later this year. Going to start my hunt for a harness though for sure!

As for a 6V coil, confused as heck. My existing coil has an external 2ohm resistor (also shown on the diagram). The resistor does nothing to the voltage at all, a single resistor can only effect current - it takes 2 or more acting as a divider to effect voltage. The coil is fed 12V at all times, the resistor is there to limit current flow across the points when the engine is running, and it is bypassed during starting to allow more current across the points, so again, very confused about 6V. Pretty much all engines with a old-school distributor needs a running resistor to reduce burning of the breaker points, but my 424 is 100% 12 volts. I just was thinking of simplification when I talked about using an internal resistor ignition coil. Modern solid-state distributors have no need for a resistor in the design, but old-school almost always have one (some internal, some, like mine, are external).

My only thought on the diode was maybe to dump excess current during powerdown, but I've pulled everything apart on my 424, and that particular wire simply connects right to ground. But, all things considered, there 'might' have been something there at some point - I'm the third owner of this 424, hard to say what has happened to it previously, but the wiring for the lights has definitely been done at some point in the past.

Appreciate all thoughts and comments !!!

 

[Jim.ME]

The 6-volt coil is a resistor of about 1.5 ohms which would allow about 4 amps to pass through the points when used on a 6-volt system. Having a 12-volt system, adding the 2-ohm (+/-) resistor in front of the 1.5 ohm 6-volt coil, will pass about 3.5 to 4 amps through the points which is the amperage common to be seen through a set of points. The wire from the R terminal of the solenoid to the coil, connected after the resistor, sends battery voltage to the coil for a hotter spark during cranking when the operating starter is pulling the battery voltage down some. A true 12-volt coil one resistor which is built (internal wires are sized and wound) to pass the 3.5 to 4 amps of current through the coil to the points. If the points are open and you test the voltage at the ends of the resistor the voltage will be the same on both ends without current flowing.

According to the wiring diagram your tractor originally had a generator and regulator, not an alternator and regulator. The generator did not need a diode, and I still do not see one in that diagram. If the generator was changed to a 3-wire alternator before you changed it to a one wire, it would have needed one in the feed to the alternator excitation terminal as I previously posted. Below is the symbol for a diode, I do not see one in that diagram.



I still think Jim Becker was on the right track that the block showing going to ground is a carb solenoid (or some other accessory) and the block before it indicates a plug together connection which was the common connection for those solenoids, which were used on many tractors. If that was a diode, depending on which way it was wired, it would either be grounding the ignition out all the time, or it would block the power from grounding at all, so I don't see your reasoning of it dumping excess current. Current sent to ground, not going through something for resistance using the current, would be a short to ground, aka "letting the smoke out".

 

[Jim Becker]

Agree with Jim.ME's comments. I don't see an appropriate wiring harness offered on this site. If you google something like "reproduction tractor wiring harness" you will locate a few places that will make a harness (maybe ignoring the eBay- or Amazon-only sources). The others will probably be able to build to order a harness that works with your one-wire alternator. Get a quote then decide if you want to go that way.

 

[Tim in New York]

Try this link - lots of comments about a vendor who will make a harness. https://www.redpowermagazine.com/forums/topic/123214-agri-service-wire-harness/

 

[Jim Becker]

All three vendors mentioned in that thread are good sources (from what I have heard).

 

[GeorgiaDave]

Actually, I said I thought it might be a TVS diode, which is two diodes back to back ->||<- It only passes voltage that exceeds the breakdown voltage of the two diodes, so during normal operation it blocks voltage in either direction. If it sees a high voltage (anything above the specified breakdown voltage) it passes that spike through the diodes, acting like a conductor. Can't imagine that this would have been in place, especially in the 60's, but the image looks exactly like the symbol for a TVS.

There IS an anti-diesel solenoid on the carb - most likely that it what is shown there as you noted.

You are correct, originally the 424 came with a generator and regulator. The generator died on me a long time ago. I replaced it with a 1-wire alternator with requires no external connections other than the single wire, which goes directly to the battery. 1-wires have built-in regulators, and limits output to under 1/2A, so it never degrades the battery (in theory). It outputs just shy of 14 volts regardless of speed.

If I do go with a reproduction harness, I'll try to find a generator and regulator and take the tractor back to originally factory specs. I know of a few places that carry OEM generators, but they are not inexpensive. That would definitely be a fun project. For the moment, it is a workhorse on my farm. Once a year I do typical maintenance, plugs, points, oil change, filters. At some point I'll probably pull the engine and do a rebuild, but it has treated me well over many years!

Thanks for all the great info - will get started tomorrow looking at a possible harness - might be my next 'winter' project.