4500 ford glo plug wiring

I have a 4500 diesel . The glo plug on the intake has been disconnected for a while because part of my wiring harness got burned . I would like to run another wire to the glo plug . How is that wired up ? Also is there a link to the wiring diagram ? I want to put in a new wiring harness later . my tractor is a 69 model with generator .

Single wire from the "heat" position of the key switch. The circuit is completed via the housing being grounded to the engine.

Also, it is not a glo plug, it is a manifold pore-heater. In addition to the wire, it also needs a fuel line connected to it. It works by heating up an electric heating element when electricity is applied, and the heat from that cause a spring loaded valve to open which in turn allows some fuel to drip into the manifold and onto the exposed heating element, which causes the fuel to catch fire, and the fuel burning heats the air in the intake and usually some of the burning fuel gets sucked into the intake valves of the cylinders when the starter spins the engine which heats up the cylinders as well.

There are pictures of the wiring schematic for that model on the internet but I don't have a link to any handy. Someone will probably come by and post one of them shortly. If you don't have a service manual, you should get one. The Ford factory service manual for the 4500 can be expensive, but the I&T FO-31 aftermarket service manual is only around $30.00. The I&T manual is for the 2000/3000/4000/5000 ag chassis tractors, but your 4500 is the same as the ag 4000 when it comes to the engine and electrical system, rear axle and other things as well. Biggest difference is the front axle and steering are completely different.

Thanks Sean , I will look for the manual . I have the cd and I hate it the , the index is a text document and you cant click on anything to go there , You just have to scroll forever to find something . then its hard to read , people have taken photos of the manual pages . Ok what is the position of the heat on the ignition ? Do you just leave it there so many seconds and then turn the starter? I am repairing the hose connectors to the heater now, thats how I found out I had a heater, the hoses started leaking .

(quoted from post at 10:45:55 10/24/16) Thanks Sean , I will look for the manual . I have the cd and I hate it the , the index is a text document and you cant click on anything to go there , You just have to scroll forever to find something . then its hard to read , people have taken photos of the manual pages . Ok what is the position of the heat on the ignition ? Do you just leave it there so many seconds and then turn the starter? I am repairing the hose connectors to the heater now, thats how I found out I had a heater, the hoses started leaking .

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he diagram that I have for the diesel shows, #1-power in, #2-accessory, #3-thermo-start, #4-ign relay/turn sig, #5-start. If diagram representation is accurate, the terminals are not sequential around it as with a clock face.
On diagram, it looks like 1, 5, 2, 3, 4. But, schematics seldom represent the physical part.

Ok what is the position of the heat on the ignition ? Do you just leave it there so many seconds and then turn the starter?

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If it still has the original key switch:

"off" is straight up
one click to the right is "run" (only provides power to the gauges and warning lights on a diesel).
Spring loaded far right position is "start".
One click to the left of "off" is "heat"
Spring loaded far left is "heat start", when released it springs back to "off" so you need to turn it one click to the right after that for the gauges and warning lights to work.

If it has the later style replacement switch:

"off" is all of the way to the left
One click right is "run"
Spring loaded far right is "start"
"heat" is halfway between "run" and "start" and you must hold the key in that position, halfway between, against the spring pressure to activate the therm-o-start.

With either type of key switch, leave it in the "heat" position for 30 seconds to a minute depending on how cold it is and how well the therm-o-start is working.

Thanks sean, I have the old style because it is spring loaded to the left same as starter is to the right . I wondered how they would do that so the heater could not be left on or stay on with the engine running . I think I like the old style better . I think I could test the heater by connecting an ohm meter on the wire connector and the ground . It should show a continuous circuit if all is well , right ?

Thanks JMOR I will check that out .

I think I could test the heater by connecting an ohm meter on the wire connector and the ground . It should show a continuous circuit if all is well , right ?

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It shouldn't measure zero ohms, that would be a dead short. And it shouldn't measure infinite ohms either. I'm not sure of the exact value, but I would guess that to get hot enough to light diesel fuel on fire in 30 seconds the cold resistance would probably be somewhere between 0.5 and 5 ohms. The resistance will actually increase a bit as the element warms up. The colder a material is the less resistance it has. At close to absolute zero most materials become superconductors.

"At close to absolute zero most materials become superconductors."

That's how the Superconducting Super Collider was to run. Every 5 miles of the 54 mile circumference was a Cryogenic generator and the
purpose was to keep the beam focusing magnets at 4 degrees Kelvin (4 degrees K above -460F....absolute zero), making them super
conductors. Reason for that was that there were so many, any resistance to speak of in the circuit and the heat and wattage required to
electromagnify them would have far exceeded the requirements to go "superconducting".

-----------I think you are closer with your 0.5 ohm estimation.

On the 4500 do the gen and oil lights extinguish when in the heat position like on my '65 3000?

Off vertical, first position CW is on, where lights come on, farther CW lights go out and the thermostart gets power, farther CW and the lights
come back on and the TS and the starter operate simultaneously.

Thanks Sean and Texas , I'm impressed , I see you guys are very knowledgeable on your electricity . I will ohm out the heater today and report back today . If it is not to hard to remove the heater , I might do that to inspect. In the mean time you can try to guess the ohms . Using omhs law E=IR at .5 ohms and 12 volts it comes out 24 amp which I think is high looking at the wire size . There is only 12 ga wire to the main switch wire "in" . At 5 ohms the I=2.4 amp which might be low . As for the watts or power Watts=Volts X Amps , so for the 24amp at 12 volt the watts would be 288 watts and for the 2.4 amps at 12V the watts would be 28.4 watts . Of coarse for exact VA you would have to add in the resistance of the wiring from the battery and the Volt charge on the battery . I don't think it would take many watts to turn a small filament wire red to burn the fuel , I going to guess at 2 ohms and 6 amp . Make you guess today !!

I don't know , my lights or instrument panel have not worked for years since the harness caught fire when the battery shorted out from not being fastened down . It sounds like you have the after market switch or newer tractor , my heat position is to the far left and is spring return to off . I am just going to run a wire to the heat for now . If I can get a wiring diag. for the 4500 industrial I am planning on a new harness and voltage reg. and instrument panel later . The ag version diag shows all the lights and other things . my tractor only has head lights , there is only one left but I think it had 2 .

I "ohmed out" the heater and it has an open circuit , infinity so the heater is fried . I took it out and I can not see a broken element but it is in an enclosure and I can not see the far end well . I was afraid from the way it looked and made in England originally that I would be spending lot of money . I was lucky ebay has plenty new ones for around $10 so I have one on the way .The figures I did in my previous reply would be for the heater in use and operating . Like Sean said the ohms are much less cold . I will post both hot and cold ohms when I get the new heater . To get the hot ohms I will have to connect the amp meter to the circuit while it is in use and the voltage at the terminal and then use ohms law to get the actual ohms . I can also get the watts from that and if it is shown on the new box I can compare .

To get the hot ohms I will have to connect the amp meter to the circuit while it is in use and the voltage at the terminal and then use ohms law to get the actual ohms .

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Or just disconnect the wire after the thermostart unit is heated up and measure the resistance directly. May not be quite as high as when fully hot, but it shouldn't cool down too much in the time it takes to disconnect the wire, especially if it's still got burning fuel in the manifold.

I don't know. It's what was in the '65 model tractor when I bought it 15 or so years ago. I had a '79 I think was the year 4600 that was different as I recall. I have the manuals on both, I guess I could check what the 4600 had. I had a MF 35 with the Perkie diesel that had the glow to the left on the switch.

(reply to post at 04:30:07 10/24/16)

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I sure am glad the rubber lines started leaking to the heater , I didnt even know it had a heater , I sure have needed that a lot in the winter . I have used a lot of starting fluid and they saw that is not good for ford tractors . I will have a heater now when the new heater arrives , before cold weather hits . By the way new holland parts view does call it a " Glow Plug "

Well it does glow. Yes the resistance goes up with temperature, common in most conductors. Actually the physics of the wire helps to make it
get hot enough to glow orange (about 1550-1750F for steel wire) and light off the fuel slobber droplets. On Dean's comment, get a helper to
return the switch to ON or OFF while you have your ohmmeter leads ready for the measurement. 24 amps for a 12 AWG conductor is not that
much, especially a single wire, non encased, short duration. Fusing current for that wire is 235 amps.

On my limited knowledge about them, I learned like you are probably learning. Bought a Ford tractor with a "Thermactor" Hootus type thing
(what's that?????), was having hard winter starting and followed the path of curiosity.

(reply to post at 06:08:50 10/28/16)

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Thanks tex ,thats some good info . Question , where did you get the 235 amp fusing for # 12 awg copper ? That is rated at 20 and sometimes 25 amp depending on the insulation . I have masters state electrical license . The only exception I know of Is to a single motor load only because of the high starting load . It is close to that of a locked rotor load . In that case you can go up to several times the running load amps for the motor for the over current protection . The reason it is justified is motors are a much better protected circuit because most all have thermal over load protection build in the motor ,and also the overload only last less that a second unless the motor is very big and they have to start slowly with a jog or reduce voltage device . Im always interested in something I might be misinformed on so let me know if you have info on fusing a #12 at 235 a . Thanks