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Had a local mower repair guy that sees a lot of 318's, 316's, etc. try to find my electrical issue. Actually, he has another guy do his electrical work. The 1990 318(P218G) had been sitting fallow for a little over a year before I gave up on chasing the issue down. He had it a few months, and when I finally got around calling to check, he said that it had been fixed for several weeks, but he'd lost my number. So, my B.S. meter was pegged, and I was just wanting to get the mower back and never have to deal with him again.

After a blade and belt change, I started mowing. In 45 minutes it quit, same as before. No power anywhere. First things I checked were the 2 fuses. Here's what the 20amp looked like -
IMG_20191005_173900363.jpg

The spade was welded into the holder...

IMG_20191005_173808556.jpg

The fuse didn't even appear to be blown.

I love this machine, I do. But, it's getting really frustrating trying to keep it running. I guess I'll give it one more shot. I've got a friend that works at a local JD dealer, and he said to avoid their shop because tracing a short like that could come close to what would be a nice down payment on a new machine. Would anyone have any idea what would burn a fuse up so badly? :flag_of_truce:
 

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If the fuse isn't blown, my first guess is you are looking at the point of failure... The fuse holder. Either way you may be replacing it anyhow.

The issue could be that if the fuse holder isn't making full contact with the surface of the blade, it will start heating up. Heat up too much and it can weld the blade in or melt the plastic of the fuse. Much like running too much current through too small gauge wire.

It could be a short but that should blow the fuse.

That is my thought without being there to look at the machine.
 

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I would look at the front PTO circuit. From the 20 Amp fuse to the TDCM back to the PTO switch, to the front PTO. There has to be a short (Check the PTO coil, both resistance and a visual inspection)
 

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Discussion Starter #4
If the fuse isn't blown, my first guess is you are looking at the point of failure... The fuse holder. Either way you may be replacing it anyhow.

The issue could be that if the fuse holder isn't making full contact with the surface of the blade, it will start heating up. Heat up too much and it can weld the blade in or melt the plastic of the fuse. Much like running too much current through too small gauge wire.

It could be a short but that should blow the fuse.

That is my thought without being there to look at the machine.
Looked closely with a magnifying glass, and the fuse element is definitely intact, so I'm thinking that the 'bad contact' angle is a good place to start. Certainly much less expensive to start with a fuse holder anyway.

Now, maybe I'm wrong but it looks like that the OEM fuse holder is sold as part of the harness, and not by itself - Part AM108845. Any problems using an off the shelf fuse holder, except for maybe the mounting spring clip not being there?
 

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Looked closely with a magnifying glass, and the fuse element is definitely intact, so I'm thinking that the 'bad contact' angle is a good place to start. Certainly much less expensive to start with a fuse holder anyway.

Now, maybe I'm wrong but it looks like that the OEM fuse holder is sold as part of the harness, and not by itself - Part AM108845. Any problems using an off the shelf fuse holder, except for maybe the mounting spring clip not being there?
Either way I think that you are forced to replace that fuse holder. You are probably right that it is only sold as part of the harness but if you can do a good job of splicing there isn't any reason that a generic fuse holder won't work. As long as you can come up with a way of securing it so it can't disappear or fall into an area where it may suffer thermal or physical damage, then there is no need for the spring clip.

I would say your biggest risk is the hot side of that fuse. If you were really concerned, you could in theory replace the wire all the way back to the power source. Battery maybe. I don't know where it is fed from. If your splice were to fail, it could be an unprotected hot wire that could short. I don't know enough about the 318 to say for sure. On my X585 they have a fuseable link right off the battery, or is it the starter that acts like a master fuse in the event there was a short before it got to the more accessible fuses in the tractor.

Lots of options at your local hardware store or Amazon for it.

Amazon.com: MUYI 2 Sets Inline Fuse Holder 10 Gauge Waterproof Pigtail Blade Fuse Holder with 40AMP ATC Fuses: Automotive

Amazon.com: JooFn Waterproof Sealed ATO ATC Fuse Holder Assembly Splice Existing Wire Kit (Pack of 6): Automotive

Amazon.com: Fastronix Automotive/Marine Weatherproof Blade Style ATO/ATC Fuse Holder with Cover: Automotive

I do agree that chasing these can be very time consuming and frustrating. I had an intermittent short on my X585 a few years ago. If I hit a bump just right it would blow the EFI fuse. I ended up pulling the hood (which is around the sides of the engine as well on that machine) and with the engine running started tapping and shaking the harness until I could get it to blow. Since it was the EFI circuit I knew it had to be in the engine area somewhere. Turns out when I had the dealer do some work on it and they pulled the engine, they routed the harness wrong and it was touching a sharp point for a bracket that is used to lift the engine out. That rubbed through the harness which is just protected in electrical tape in that area as it is routed up to the fuel injectors and a couple sensors. I peeled back the electrical tape and saw a tiny rub mark through the insulation for one of the wires that traced back to one of the fuel injectors. It all added up. I used liquid electrical tape to seal the nick. Regular electrical tape, then I put that section in a wire loom and zip tied it so it doesn't move. Haven't had an issue since. It took a while to find though.

This failure, at least with the fuse appears to be poor contact in that fuse holder. Even if you tried to pull out the blade that "welded" in there you will never get the contacts clean and it will do it again. I am sure at this point in addition to the dirt and grime you have melted plastic in there. That is why I say the first thing that needs to be done is address the fuse holder. Not saying you don't have another issue but I don't know all the history of failures on your machine and what you have tried.
 

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Steve, Check local auto parts stores for a blade type fuse holder, should be about $4. They can be found with 2 pig-tails and can be spiced into existing wiring. After installing new fuse & holder, ohm out pto coil...should be around 3.7-4 ohms. Bad windings get worse as they are used and are known to blow a fuse. Bob
 

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Steve,

Your present issue is replacing the fuse holder, and you should inspect the wire sourcing it all the way back to the key switch if possible. Below is the wiring excerpt that shows the fuse connections. F1 is the 20 amp fuse...

ignition diagram 318.JPG

While the pictures you posted above show that the fuse holder is the failure that halted your mowing session, I suspect that this may not have been the only the reason you had the tractor in the repair shop originally -- what were that symptoms you were chasing then? If it was the occasional loss of electrical power, then maybe a loose connection at this fuse has been an issue for some time. So do let us know all the symptoms you originally observed.

Do you have the TM1590 shop manual (the above excerpt is from that document...) as it has lots of diagnostic procedures and has the theory of operation of all the electrical and hydraulic sub-systems. This forum has lots of folks that can give excellent experience-based advice as well, as does our sister site Weekend Freedom Machines.

Once you get the fuse holder replaced, please report back as to what other symptoms you still are chasing.

Chuck
 

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Steve,

Your present issue is replacing the fuse holder, and you should inspect the wire sourcing it all the way back to the key switch if possible. Below is the wiring excerpt that shows the fuse connections. F1 is the 20 amp fuse...

View attachment 708142

While the pictures you posted above show that the fuse holder is the failure that halted your mowing session, I suspect that this may not have been the only the reason you had the tractor in the repair shop originally -- what were that symptoms you were chasing then? If it was the occasional loss of electrical power, then maybe a loose connection at this fuse has been an issue for some time. So do let us know all the symptoms you originally observed.

Do you have the TM1590 shop manual (the above excerpt is from that document...) as it has lots of diagnostic procedures and has the theory of operation of all the electrical and hydraulic sub-systems. This forum has lots of folks that can give excellent experience-based advice as well, as does our sister site Weekend Freedom Machines.

Once you get the fuse holder replaced, please report back as to what other symptoms you still are chasing.

Chuck
I was looking at the schematic. What is the stuff in the lower right? The seat switch and brake safety stuff? The ones labeled A B C D
 

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That is the items inside what is called the "TDCM" aka Time Delay Control Module which monitors the safety switches and will shut down the engine or not let it start if operating conditions are not correct for safe operation of the tractor/mower. Those items are outlined by a square box label A1 Time Delay Control Module on the diagram. physically it is a black box mounted to the steering column under the battery tray.
 

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It appears as though your fuse holder is corroded. Based on the good side. Or maybe a bad connection in the fuse holder. That will burn the fuse on one leg and not blow your actual fuse because the current cannot get to the other side.That is not saying you still have an issue with something shorting out. But I would start there.
 

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That is the items inside what is called the "TDCM" aka Time Delay Control Module which monitors the safety switches and will shut down the engine or not let it start if operating conditions are not correct for safe operation of the tractor/mower. Those items are outlined by a square box label A1 Time Delay Control Module on the diagram. physically it is a black box mounted to the steering column under the battery tray.
Got it so the switches send their signal there. The way they do it in newer machines is to hook them up in series so if the chain is broken the relay for the PTO drops power. Basically in series on the coil side of the PTO relay.
 

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Discussion Starter #12
Figuring that the least expensive attempt at a fix was to replace the fuse holder, that's what I did, and that has done the trick!
 

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Hopefully that takes care of it for you...

(y)
 
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