12V conversion -- solenoid hookup?

I've just finished fixing a blown head gasket on a used 850 I bought some time ago and milled the head 2 weeks ago, got it running, etc. But the wiring was a mess and I'm trying to straighten it out. Need some help.

It had a 12V conversion w/1 wire alternator and electronic ignition. A key switch was added, and a separate starter button also on left side of dash.

I have a new 4 wire solenoid. Two big terminals and two small. One small is labeled "F" and one is labeled "S".

I have two heavy wires coming in, one to Batt positive and one to Starter motor. I know those go on the two big terminals.

I have 3 smaller wires coming in. One used to be connected to S and the other two with big ring terminals used to be connected to the Batt+ big stud terminal. There was nothing on the "F" terminal.

I suspect that the last owner didn't have this wired right because the tractor tended to start when the starter button was let off. I think I've seen something somewhere that say that the "S" terminal wiring is at fault if this is happening.

What should S be connected to.

A schematic for the above type system would be great if anyone has a link! I've googled about a dozen schematics, and none of them shows my situation above -- particularly the 4 wire solenoid and 1 wire alternator combination.

Thanks for your help!

An 850 should have had only a 3 terminal solenoid, so first off you have the wrong solenoid. Second, if you really want to incorporate a 4 wire solenoid, you must know which of several 4 wire solenoids that you have. Some 4 wire will not permit use of neutral safety start switch. I & S are connected differently on different 4 wire solenoids. What do you have? Life is never simple, ya know.

No it isn't JMOR! I will check the solenoid and report back in a few minutes. I got a 4 wire Ford solenoid because a 4 wire was already on the tractor.

What I'm going to do now besides get the solenoid number and type is draw up a schematic of what I have and post it here. That might make talking about it a lot easier.

Back shortly.

What it was like when it left the factory:
Solenoid PN NCA11450A

Thanks JSTOR, but I don't have that system any more and won't be restoring to that. I need to work with the present system which is 12V neg ground, electronic ignition, alternator and replacement switches, etc.

Here is the present system, as found. I've included on the drawing the 4 wire solenoid type and specifics.

I'd like to know if this is correct, particularly in the solenoid connection, or if it looks like there is a problem in it. (Note, the coil is marked "12V -- does not need a resistor".)

Thanks for all help!

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Practically all (NEW) typical solenoids nowadays have four terminals....


The most common Ford solenoid(S5049) has a small paper insert that instructs the user
to disregard the extra terminal (usually designated 'I')

You stated..."I have 3 smaller wires coming in. One used to be connected to S and the other two with big ring terminals used to be connected to the Batt+ big stud terminal. There was nothing on the "F" terminal."

That should be correct, in that the starter switch wire connects to the 'S' terminal.

The other two 'large ring' terminals joined the
large BAT terminal to supply power to some other area....

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Sorry, JMOR, not JSTOR, and also obviously not a one wire alternator........

Thanks Little Billy! I just posted my schematic as found, and saw this post after.

So it looks like things are okay as is? Probably the problems I had then were due to bad terminals on wiring, etc. which I'm renewing, and the bad older solenoid.

Absolutely nothing has to be changed relative to the solenoid when installing a 12 volt conversion. There's no reason to get an incorrect replacement solenoid other than somebody not asking the correct questions( buyer OR seller). Which happens often when purchasing tractor parts at an auto parts store. There's a reason they are called auto parts stores.

All local tractor dealeships have closed in the last ten years withing 50 miles of here.

Sometimes getting a modified working tractor going takes precedence over restoration research and waiting for mail order

But the part in question was not bought at an auto store, but purchased from Tractor Supply, which just opened across the state line.

Surprise, nobody there is familiar with a 12 volt upgraded 1954 Ford 850. They had a couple of solenoids, I chose one that matched what was already on the tractor.

It works, and has one terminal that isn't necessary. Big deal.

You have a nice day.

So long as the solenoid and the neutral safety circuit work, I agree.

I believe the tractor will start in gear as it is wired now, with key switch and push button. That does not seem to bother some folks.

(quoted from post at 22:53:30 06/01/14) I believe the tractor will start in gear as it is wired now, with key switch and push button. That does not seem to bother some folks.

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recisely why I hate the word "upgrade". More like a step backwards .......a 'down grade' perhaps.

(quoted from post at 10:40:46 06/02/14) Precisely why I hate the word "upgrade". More like a step backwards .......a 'down grade' perhaps.

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I haven't used the word "upgrade" in relation to this tractor. I showed the wiring as it was on the tractor, as received, and asked questions here, not at an "auto store." Presumably to friendly knowledgeable tractor folk who would be willing provide answers and explanations, rather than put downs. This is a new tractor to me, and a new brand for me. It's been messed with by former owners. Sorry, that's the situation.

If at one time there was a safety switch setup on this Ford that prevented starting while in gear, that would be preferable to none, to me, okay? I have no objection to it, and I'd be happy to look into adding that back if the last idiot who owned this thing added that to his screw up list of modifications that I've gradually straightened out, as I've started to get this machine running and working again.

This is not a restoration project, it's a tractor that will be worked. And though I'd be happy to add back a safety interlock, let me point out that my regular working tractor, a 1951 Model M John Deere has worked daily for the last 12 years building a house, digging a pond, hauling logs, chipping brush, building a bridge, and plowing snow 600 feet of drive up a mountain in Vermont winters. And it never had a safety switch interlock to begin with. That doesn't horrify me. I'm not about to stop using my '51 Deere M just because the '54 Ford 850 came with some kind of safety switch that somebody later removed.

Personally I find that sitting in the seat of a tractor, putting it into neutral and depressing the clutch before hitting the starter makes good sense, rather than depending on a mechanical device to remind me. Which in this case must have broken somewhere along the line, with untold results for somebody.

So okay, are we straight? Help is appreciated, but I don't need jibes just because I ask a question about something I don't know here, and about a problem I didn't create. That's why I asked here in the first place.

Thank you again to all respondents who helped.

btw, I've been in a couple situations with the Deere over the years on an icy hill with a stalled motor and brakes barely holding when I've been damn glad I could just hit the clutch a moment to try to re-start, rather than shift out of gear to do it. If she didn't re-start and slid, at least letting up on the clutch with a dead engine would help stop you.

"Surprise, nobody there is familiar with a 12 volt [u:5e6e2bb554]upgraded[/u:5e6e2bb554] 1954 Ford 850." Hey, I didn't tell you what you can & cannot do. I did post the original diagram with the neutral safety start switch & part number, which you immediately dismissed. After the "JESTOR" (jester) response, I pretty well left it to the others. Yes, I saw the apology. The downgrade & step backwards is not a put down, just a fact. Been decades since any mfgr sold tractors without safery start switch, 1939 0r 1940 for Ford. Later for some others like my 1954 SMTA which still didn't have one. Like your JD, it hasn't hurt me or anyone else........yet. If after you get it running, you can't shut it off, please feel free to come back for pointers that I might have made had I not been shut down and you & Little Billy decided everything was a OK. Have a nice day.

I didn"t shut you down JMOR. And JSTOR was a mistake not an attempt to call you a jester! JSTOR is a repository for digitized technical texts that I confused with your name.

I realize you"re outta here by now, but I don"t want to leave it as something I didn"t say or mean at all.

Looking back over this entire topic I also see where you seem to think I was dismissing you. Where I wrote "No it isn't, JMOR"

But I was agreeing with what you wrote: "Nothing is simple." I was agreeing with you, not dismissing!

And then I went out to get the part number you asked for and to draw up a schematic for you, expecting it would be easier to talk about and there would be some explanation. But you never said a word after that, until the "downgrade" comment.

Well at least I've straightened my side of this out. I would appreciate it if you do want to talk about the lock out circuit further. If not that's okay then.

So it looks like this lockout circuit works the following way: A switch to ground, located on the transmission top is locked out when the shift lever isn't in neutral. The switch completes a ground to the solenoid, which must be hot on the other side of the coil therefore to complete. Depending on the construction of the particular solenoid, the coil might or might not be connected internally to ground or to the hot terminal. This is why you said that the part number was important and asked for it. And the reason you said that if I got the tractor running I might not be able to shut it off. Is that correct?

(quoted from post at 16:34:13 06/02/14) So it looks like this lockout circuit works the following way: A switch to ground, located on the transmission top is locked out when the shift lever isn't in neutral. The switch completes a ground to the solenoid, which must be hot on the other side of the coil therefore to complete. Depending on the construction of the particular solenoid, the coil might or might not be connected internally to ground or to the hot terminal. This is why you said that the part number was important and asked for it. And the reason you said that if I got the tractor running I might not be able to shut it off. Is that correct?

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ell,......... face to face or even telephone conversation sure beats the h3!! out of simplex texting/messaging! Such miscommunication/misunderstandings would be cleared up immediately. You got it correct on the solenoid situation. The may not shut down has to do with the alternator powering the ignition after you turn off the key. If something isn't done to prevent it, the alternator excite #1 terminal will back feed power to coil & engine will keep on running. Usual method is a diode or a small lamp (charge warning/idiot light), or a 10 Ohm resistor in the wire between ign switch & alt #1. Any of the 3 work to prevent or reduce power below the level needed to make ign keep going when you turn off switch.

Folks on here are reluctant to advise anyone to bypass a safety device/item. We all know there are thousands of old Ford tractors operating safely every day without the neutral switch.

The original 6 volt single post solenoid would probably last a long time. A 12 volt 4 post solenoid with insulated base would work too. I do not have a part number handy. Some 4 post solenoids use the fourth post(I) to put full 12 volts to ignition coil during starting. They usually have a grounded base, i think.

JMOR does not act like a 'guru', in my opinion. He just really knows this stuff. Very, very knowledgeable on many topics. I always read his posts.

Thanks JMOR, I appreciate your help, and apologies about my side of the miscommunication. I do want the safety start feature and tested the switch on the transmission, which was covered in old paint. I scraped it off and tested with a multimeter while shifting. It"s still functional.

So I"m going to remove the push button on the dash that the prior owner(s?) added, and I am going to return the solenoid to Tractor Supply, since never used it.

I did test it with an ohmeter and verified that internally one end of the coil is connected to ground. That wouldn"t work with the safety switch -- I would have to isolate the case and run a wire to the switch for the ground, which doesn"t appeal.

I didn"t see a 3 terminal Ford solenoid there last time, so if I can get one there I"ll have to order it.

I would shake hands with you if you were here, and offer to buy you a coffee at the country store, but for this internet thing in the way!

Thank you.

(quoted from post at 22:37:52 06/02/14) Thanks JMOR, I appreciate your help, and apologies about my side of the miscommunication. I do want the safety start feature and tested the switch on the transmission, which was covered in old paint. I scraped it off and tested with a multimeter while shifting. It"s still functional.

So I"m going to remove the push button on the dash that the prior owner(s?) added, and I am going to return the solenoid to Tractor Supply, since never used it.

I did test it with an ohmeter and verified that internally one end of the coil is connected to ground. That wouldn"t work with the safety switch -- I would have to isolate the case and run a wire to the switch for the ground, which doesn"t appeal.

I didn"t see a 3 terminal Ford solenoid there last time, so if I can get one there I"ll have to order it.

I would shake hands with you if you were here, and offer to buy you a coffee at the country store, but for this internet thing in the way!

Thank you.

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ou are more than welcome & I too regret the miscommunications problems. Come back anytime. I don't know what a "guru" is supposed to "act" like? I didn't give myself any title beyond "JMOR'.

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you & Little Billy decided everything was a OK.

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WHOA, What prompted that?

My comments were based on solenoid hookup only,
and no inference was made to entire circuit being OK.

You're putting words in our mouths.......
'assuming' we said something else

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