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Discussion Starter #1
My MF 4880 hasn't been run for 3 months, went to move it today...It kept shutting down, no idiot lights would appear on dash...Then the alt. and engineoil and trans pressure would come on and I could start it....they would click on and off once they stayed on it could be started...but would shut down for no reason that I can see.. what is it a faulty sensor Trans.pres.
is there relays that run these sensors, as I can hear something clicking in the dash, before the buzzer starts screaming...and before the lights come on... I hope I explained it...Thanks Neil
 

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The only relay I have had to replace is the one that runs everything in the top of the cab.The first thing I would look at is the key switch I have changed alot of those.If things are right turn the key to the start position with out the the clutch in and ALL the warning lights should come on.In the on position with the engine off only the red lights should come on.Look at the back of the switch see if the wires or post are loose.Anything that momentarily cuts volts to the soliniod will shut the engine down.
 

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I went to the shop and got my book and there is a starter relay and a alternator relay I remember I have changed the alternator relay once in my life.The power for the fuel solenoid goes through the alternator relay and is in the dash easy to replace.I would still look at the key first ,good luck and let me know what you find.
 

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Discussion Starter #4
I went and checked the key switch and the wiring, everything seemed to checkout ok...started it up and let it warm up...seemed fine took it for a drive.........didn't get far, shut down and wont reset the fuel shutoff...went and got a starter relay, will install in the morning...can hear a relay or something clicking in the dash, hope it is the relay(cheap and easy) that is the fix. will let you know what happens..anyother ideas?............Neil
 

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Hey Neil

If your tractor is shutdown in the bad spot (middle of the road) there is a knob you can turn up by the fuel solenoid to manually turn on the fuel but your tractor will not shutoff with the key until you turn it back out.

I have to use mine every once in a while when I try to start the engine
While cranking I get no smoke, turn in the knob and she fires right up. It has not got annoying enough to fix yet



Good Luck I bet onionfarmer is on the right track

KS8780
 

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ks 8780 I have a 4880 that has does what yours does and sometimes it won't start.I have changed the solenoid and it made no difference.But if you open the throttle full and then Start the engine it works every time and you don't have to get out and turn the knob.I keep my hand on the throttle and pull it back as soon as it fires.
 

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Discussion Starter #7
not the starter relay or key switch, changed both...will try the alternator relay next, could be a cracked wire as sparrows have fallen in love with it like to roost under the hood... thanks guys I'll let you know what I find..........Neil
 

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I think it is the alternator relay and not the starter relay but if you have the starter relay you can try it. Check the wire starting at the solenoid back to the cab make sure it is in good shape.And just for fun put a volt meter on the alternator and see what it says. good luck and let me know what you find
 

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Discussion Starter #10
can't find the alternator relay, where is it located...is it what I call the starter solenoid located on the engine side of the firewall(left hand side) looked in the book no mention of a starter solenoid leads me to think(that isn't always good"me thinking") thanks ........Neil
 

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Northern Farmer
The alternator relay in the dash in the cab. Take the top panel off and I think its to the left and front.I will look the part number up and post it later to night as I am running late. later, Steve
 

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Discussion Starter #12
I guess I replaced the alternator relay. the one in the dash(left side of circut breakers) didn't fix the problem..Tractor will not run at all now, the fuel shut off wont stay on long enough to get the tractor to start. the starter relay is outside on firewall?(looks like a starter solenoid for a gas engine) If that doesn't do it what next? any ideas? Neil
 

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Before we replace any other parts turn the knob on the fuel pump to turn on the fuel and start the engine.You won't be able to shut it off unless you turn it back.Have a volt meter and check to see if theres power to the fuel solenoid check to see if its charging,check in the dash to see were you have power.If I remember right the starter solenoid on the firewall supplies power to some off the dash.With the tractor running see if you have power going through the starter solenoid (the two big wires) and there should be power two one of the small wires.let me know what you find Steve
 

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May be the fuel shutoff solenoid has gone wacky. I suppose you could hot wire the solenoid as a test.

As for the starter solenoid on the firewall I don't think it does anything except trigger the starter solenoid on the starter. If it did supply power to the dash it would have to stay one constantly and it would not last long.

But..I could be wrong on that


I think I am going to go and look at my wiring diagrams to refresh my memory

Good Luck
 

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Discussion Starter #15
in a real pickle, can find this knob on the pump near the fuel shutoff, must be blind.... batteries were dead this morning as if something was drawing the juice from them....tried to boost but the starter wouldn't disengage when the key was turned off. just kept turning over smoke coming from the jumper cables they were getting rather hot by the time I got them off....I was hooked to the starter, would that cause this? took the batteries out and tested them almost right dead.. recharging them today then I'll test to see if they are still good. never got to test anything with volt meter..... that was my day any suggestions or ideas.....Neil
 

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Well I wish I was a little closer I would come take a look but thats not possible.So get some batteries in it and see what happens.The knob on the pump points to the back of the tractor on top.Before you start it turn the key to the ON position and see if you have power to the fuel solenoid.If you do and it does not start it could be the fuel solenoid.Now turn the fuel on with the knob on the pump ,start it and check all the things we have talked about with a volt meter. good luck Steve
 

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Discussion Starter #17
Guess what? No knob, I think it must have been removed, a plastic cover was put over where it is suppose to be...looks like I might be able to use a screwdriver to turn the stub shaft that the knob was attached to. Batteries weren't completely charged this morning so I'll check it out again tomorrow....Neil
 

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Neil

The plastic cap covers the drive if you have a mechanical tachometer.Stand on the right side of the tractor and open the hood.Run you hand along the top of the pump about mid way and down on the left side you will find it.It is as big around as a dime.If there is any older Cummins engines around like 855 it will have a PT pump and you can look at those and find the knob it will be the same on a 903.The part number of the alternator relay is 771 354 m1 .
 

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Like onionfarmer said knob is there. Should be forward of the tach drive you have found. about the size of a dime and knurled. I can take a pic if you need it .
 

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Discussion Starter #20
thanks guys: found the knob, had to replace the starter relay and one battery...alternator is only putting out 12.8 volts so I have a service guy coming to check it out....I've heard that alternators are expensive for that tractor. hope it is something I've overlooked. belt is tight and I can't think of anything else to check or do.....Thanks again guys you were a big help.....Neil
 
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