Help With JD 318 please

[wdenton]

Thank you for the information and you are correct on the fuse.
I will give you a quick update on what I have found

The 2 am fuse was blow so I replaced and it still would not start so I did some digging and also found a 20 amp fuse that is tied to the key switch and that was blown
I replaced it and the tractor runs (yah)
but when I engage the blade (pto ?) switch the 20 amp fuse blows almost instantly. The tractor drives and runs fine it the blade is not engaged

I am thinking the switch is bad but I have not figured out how to meter it or check continuity on it.
The switch looks like a sten with 5 post and all 5 post seem to be used.
so one connector has 2 wires and the other connector has 3 wires
they look like this

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A new switch is around 30 bucks so I would like to make sure this one is bad first and that it is not a wire that is ground out when I engaged the switch

Any help would be greatly appreciated.

 

[wdenton]

the format of the swtiches didn't come out

lets try again
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[Amvcane]

Never attached a file before, but here goes.

View attachment 318 Tm1590 schematics.pdf

you may have to check the wiring of the pto switch.
also the pto coil may be shorted, check resistance to make sure coil is not shorted and blowing fuse.
find the full manual and download.

 

[wdenton]

Sorry the link is not working.

If you like you can email it to me at wdenton07@gmail.com

I appreciate all the help I can get in fixing this.

When you say the PTO switch are you talking about the one I flip to turn on the mower deck that is currently blowing the fuses?
Or is there another switch I need to look at also?

 

[milligjg]

There is a tech service bulletin on starting issues for these tractors. Sometimes mine won't do anything, sometimes it will click and other times it fires right off.

John Deere Starting Improvement Relay Kit - AM107421

 

[BKBrown]

If fuse blows when you engage the switch for the mower PTO clutch-- there may be some of the wiring insulation that has worn or rubbed and is touching metal (grounding). Look closely at all the wires you can see and check if they are grounding out on something.

 

[bjr]

And OR a clutch went grounded (short circuited). There are various relays witch will show up in that schematic. bjr

 

[Yellowfever440]

On the pto clutch that is bolted to the front of the motor. Pull the grille and side panels off and find the 2 wires coming out of the clutch up front and trace them back to the switch and make sure they aren't worn or bare like the other person mentioned. One may just go to the frame for a ground and the other should go to the switch. Check the ohms and then switch the switch on after unplugging the connector at the pto. If the fuse still blows when it's unplugged it's something before there or the switch it's self. I can't say I have ever seen a switch go bad and blow a fuse on a 318

 

[monster318]

Also, Many times I have seen where the plug that plugs onto the back of ignition switch get hot, melt and distort, sometimes even fusing itself right onto the ignition switch. This has happened to, my grandfather's, My Fathers, and my own 318 (also seen it on 300 series tractors at swap meets). Each time caused them to have a no power situation. I know the power for the front PTO runs through that switch as well..What I did to fix all of ours was to take insulated female connectors, crimp them onto the wires and reconnect them to a new ignition switch noting which terminal they came off of originally and making sure they land back on the correct terminal. Havent had a problem since.


Maybe something in there is touching something it shouldnt be...

Also if your tractor takes the round glass type inline fuses where you had said you found the 2amp and 20amp fuse, I recommend swapping them out to the square push in type fuses, the round glass ones are also a known hot spot prone to melting on these tractors.

 

[wdenton]

Thanks for all the suggestions.
I got her up and running now

I took of the electric clutch and metered it out and it was getting .02 so the coil was shorted.

I ordered a new clutch and put it in and it runs like a champ now.