# 1968 Ford 4400 Solenoid Switch



## Gemini1 (Jul 28, 2011)

Hi All, Replacing the solenoid on the 4400. Got a M 40 Lucas type solenoid from a starter shop which they say will work. This is for a M 50 starter. The M 40 has 2 terminals and the M 50 has 4 terminals. The M 40 works partly: turn the key to the right starting position and the engine roll over. Turn the key to the left, thermoplug, starting position and nothing happens. My question is, Will the M 40 work on this starter and does it have to be wired differently. I think I may be out $60 if they won't take it back. thank you for any help you can give.


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## Fedup (Feb 25, 2014)

I'm not quite sure just what it is you're asking for here. If the starter will engage and operate when signal is applied, then what's the problem? As for the switch and wiring, that's another matter. One can't blame the solenoid/starter for not working if no signal is applied.


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## BigT (Sep 15, 2014)

Howdy Gemini1,

Welcome back!

As I understand the keyswitch function, when you turn the key to the left, the thermostart intake manifold heater is heated up (turn further left and starter is engaged). This is for pre-heating the thermostart prior to cranking, especially for cold weather. It injects heated diesel into the intake manifold. Some say it injects fire into the intake manifold. I never took the time to check it out.

Since it cranks when the key is turned right, I would say the solenoid is OK. Turning the key full left should also engage the starter. Maybe you are missing a jumper connection at the keyswitch, or maybe the switch is bad. I'm certain they only use one wire from the keyswitch to the solenoid. Turning the key full left or right makes the same circuit (maybe a jumper wire or perhaps internally inside the switch) to the starter. 

My tractor does not have the left position on the keyswitch. I have a pushbutton for preheating the thermostart. Others have to hold the switch to the right midway in the spring loaded position prior to cranking.


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## Gemini1 (Jul 28, 2011)

Hi guys, thanks for the replies. I going to try and load a couple of pictures of the solenoids. The first photo is the same as the one I got from the starter shop, which they said should work. It's still on the tractor at the moment. The second photo is the same as the one I took of the starter, which is the same as the Lucas M 50. BigT your right about the thermostart plug. It does burn the fuel in the manifold. Quite a little flame in the manifold, I've acturlly heard it pop when it ignites. I don't know, maybe I held it on too long. Anyway, I may put the old solenoid on again tomorrow just to see if it works. Thoughts and advice always welcom. Thanks


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## sixbales (May 18, 2011)

On my Ford 3610, I have the following connections to the solenoid:

1) Battery cable to the large battery post of the solenoid.
2) A brown wire, maybe 10 gauge, from the above battery connection above to the power input terminal of the keyswitch.
3) A black wire to the spade on the solenoid, from the keyswitch "start" position.
4) A heavy copper jumper from the other heavy terminal on the solenoid to the post on the side of the starter. 

Looking at your old solenoid, there are other posts & spades on the solenoid....Do these have wires going to them?? 

What was your problem that caused you to change solenoids in the first place?


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## Gemini1 (Jul 28, 2011)

Hi sixbales, thanks for the reply. Sounds like your 3610 has the same wiring setup on the solenoid as the 4400. Battery cable and 10 gauge brown wire on the large post.I have a red wire going to the spade terminal, and the large copper jumper to the stud on the side of the starter. The two large spade terminals on the large post are not used. The starter shop told me they were for future use, whatever that might be. Also, one small post is not used. don't know what purpose it would serve. I didn't get to look at it today. I was helping a friend pull his pump out of the well, in the rain. Tomorrow I'll put the old solenoid back on the starter and see if the Thermostart works with it. It did before I took it off. The reason I wanted to replace the solenoid is that it doesn't always engage. Sometimes it just clicks and you have to turn the key 6/8 timed before the starter engages. So we'll see what happens. thanks again.


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## Fedup (Feb 25, 2014)

I believe swapping solenoids again would be counter productive. If the original had a problem why put it back on? If you now have issues with the operation of the thermostart, it's a matter of switches and wiring. Most likely something you disturbed in the process, but it's not the starter solenoid. I believe you're viewing the problem from the wrong direction. Neither the starter nor solenoid have any connection to the thermostart other than the wire to the unit at some point runs through the same harness.


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## Gemini1 (Jul 28, 2011)

*1968 Ford 4400 Solenoid Switch - Update*

Fedup, thanks for the reply. You were right that putting a defective solenoid back on the tractor, even if it worked the ignition switch properly, would be a waste of time. I'd only have to get a new one because it only works part time. So I got a new M 50 Lucas style solenoid and now the Thermostart side of the ignition switch works fine. Thanks all for your thoughts.


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