2018 John Deere 5055E Ignition Switch Fuse blows

[Jkwc06]

My ignitions switch fuse blows as soon as I turn the key on. The tractor ran just fine a week ago went to start it today and this is happening. I have googled it and everyone talks about the cold start advance sensor that is on the thermostat housing. Mine is a newer model than all the ones in the videos and I can't locate where mine would be.
Anyone have any ideas on location or what the issue could be?

 

[Roadworthy]

I don't think it's the cold start advance, whatever that is. It's possible mice have been working on your wiring. They tend to seek shelter as the weather cools. Try to locate a schematic diagram for your tractor. That will show what the ignition switch controls. It sounds like you have a wire shorted to ground.

 

[Jkwc06]

That was the first thing I looked for and didn't see any evidence of anything chewing on any of the wires. So I went to the internet and found everyone saying John Deere has had the issue with the cold start advance since the 90's.

 

[beenthere]

Jkwc
Put a light in the fuse slot that is blowing. The go poking around for the short.
If there is a fuse slot (pic would help showing the fuse that blows), then I rig up a 12v bulb on a blown fuse and put it in there, as the bulb will be lit until you remove the short.
Pic of the rigging I use..

 

[Roadworthy]

I thought about the bulb for a fuse trick. The problem with that is turning on the ignition switch is supposed to cause current to flow. Depending upon the choice of bulb normal current may be enough to cause it to burn brightly. You will probably have to break out the individual circuits controlled by the ignition switch and test them one at a time. The bulb may only mean you don't have to replace a fuse every time you turn on the ignition while troubleshooting.

 

[Jkwc06]

So I pull the whole dash apart, harness looks good everywhere. Loom is still intact. I isolated the dash from the engine compartment fuse still blows, removed all switches, relays and solenoids under the dash only had key switch plugged in and fuse still blows..... So I am thinking bad switch??
I did a round about version of the light bulb test and the wires on the back side of the switch got hot very quick.
Anyone have any other thoughts.

 

[beenthere]

I thought about the bulb for a fuse trick. The problem with that is turning on the ignition switch is supposed to cause current to flow. Depending upon the choice of bulb normal current may be enough to cause it to burn brightly. You will probably have to break out the individual circuits controlled by the ignition switch and test them one at a time. The bulb may only mean you don't have to replace a fuse every time you turn on the ignition while troubleshooting.

To me, not needing to replace the fuse every time is a real payoff.

"may be enough to cause it to burn brightly".. suggests that it is a direct short, and helpful to the troubleshooting.

"have to break out the individual circuits ... to test one at a time" is the way to trouble shoot the problem. When you do that and the bulb goes out.. Bingo!! you have found the problem.

Maybe I am missing something, but break out the individual circuit or wire by wire is a way to track the problem down.

 

[Lineman North Florida]

My money is on a bad sensor, probably temperature sensor, to many E-Series tractors have this problem , mine did and that was exactly what it was.

 

[Jkwc06]

My money is on a bad sensor, probably temperature sensor, to many E-Series tractors have this problem , mine did and that was exactly what it was.

I disconnected the entire engine harness and it is still blowing the fuse. Mine doesn't have the cold start advance sensor in the thermostat housing like the older models have.

 

[Lineman North Florida]

I disconnected the entire engine harness and it is still blowing the fuse. Mine doesn't have the cold start advance sensor in the thermostat housing like the older models have.

But does it have it located somewhere else? If I was sure that it does not I would move onto other sensors like the Park/Neutral sensor as that 20 amp ignition fuse is probably tied into most of the sensors on that tractor, if this tractor is newer it would probably be worthwhile to talk to one of the mechanic's at your JD dealer, because at this point we are just guessing over the internet. Whatever happens let us know what it turns out to be for future reference. Good luck. Charlie.