4100 blowing the fuse for the glow plugs and starter circuit

[jscheumann]

I seem to have a short in the circuit for my engine glow plugs and starter. As soon as I turn the key to the on/run position (not far enough to engage the starter), it blows the fuse.

I can't figure out what exactly is causing the short. I've disconnected the coolant temperature sensor, the glow plug module in front of the radiator, the alternator, but it still blows the instant the key is moved from the off position.

Does anybody have anything for me to try/check?

Jerry

 

[beenthere]

Fix up a tester that you can plug into the fuseholder. If it is a spade fuse, I take a blown one, solder a wire to each leg and then to a lightbulb socket at the other end. Put a 12v bulb in and plug it into the fuse slot. If the light is on, then there is a short. Helps to poke around removing or moving wires to fine where that short is located (when the light goes out).
Saves a lot of frustration trying something and then blowing another fuse when it doesn't happen to be the problem.

Hope this helps.

:welcome: to TBN

 

[DFB]

Is it the F2 fuse? Or the main fusible link that's blowing?

If it is F2 the book says most all the safety switches the gear selector neutral, seat switch are also on that same keyed power circuit along with the fuel gauge, sensor, control module, PTO switch and relay, in addition to the alternator/regulator, glow circuit and engine coolant sensor you have already isolated.

Sounds like a direct short so I would definitely check the seat switch and gear range selector wiring first before taking the console apart. Been there done that...more work than I like to do

 

[jscheumann]

It's the F2 fuse. It's not a direct short. I pulled the lower dash front loose so that I could get to the wires behind it. I rigged up a test light as suggested by Beenthere, but jiggling wires and harnesses got me nowhere. So I pulled the connector behind the ignition switch and found the white/black wire had 3000 ohms of resistance (I temporarily put a good fuse in place of the test light), but with 12v, that should have only drawn 4milli-amps - and NOT blow a 10amp fuse.

That wire feeds:
K2 glow plug relay
K7 safety relay
V1 diode
S8 PTO Switch
X6 (P1 fuel gauge, H6 engine oil pressure light)
K6 Engine coolant temperature light and park brake light flasher
X9 (S7 rear PTO switch, S6 seat switch, X24/V3 diode)
X3 (A1 glow plug module) - this is the only thing I'm pretty sure is NOT it - I unplugged this and no change

I'll try unplugging more stuff tomorrow when I get home from work, to try to narrow it down. I ran out of light tonight, and the tractor is on the side of a hill in the middle of the yard. Plus I needed to study the wiring diagram in the technical manual I got from joecdeere (thank you!) to see what that wire was feeding.

 

[Thruxtonguy]

4100 friend:

Mine did this, too. We check the wiring path and found that the factory had run the glow plug wires under the air cleaner, which in turn had lightly pounded them from normal vibration until one of the wires wore through. Exasperating to find, but easy to fix. Problem solved.

Dr. Gwinnt