6405 cab tractor

[kcwatkins731]

i have 6405 cab tractor that blows 30 amp ignition fuse when key is turned on. any help would be appreciated. also a wiring diagram would be a great help. this fuse kills all power to ignition all lights go out in dash key does nothing.

 

[Zebrafive]

I would start with seeing the dealer and see if they can print out a wiring diagram for that circuit.

Sounds like something is shorted to ground.

Absent a wiring diagram, I would disconnect the ignition switch. Use a test light to determine what wire supplies power to the switch. Then disconnect the battery and use an OHM meter and check all the other wires in the connector and see if any show zero OHMs meaning that wire or what it connects to is shorted to ground.

Good luck.

 

[bigbull338]

you have a major prob on your hands.id take to the dealer an let him fix the prob.

 

[jenkinsph]

I agree with Zebrafive, you will need to find the short, and I assume this is your purpose in inquiring about the schematics.

Might be as simple as a crushed wire grounding out to the frame but good diagnostic skills should find it rather quickly. If you don't have a clear understanding of electrical basics then I would think this problem would be a good candidate for a dealer service call by their electrical guru. No reason I can see to pay to haul this tractor to the shop.

 

[bakjr]

I have a 6410 and had the same problem with blowing the ignition fuse. After starting, it would run for a couple minutes until it started to warm up; then the fuse would blow. Turned out to be a temperature sensor on the thermostat housing.

 

[Zebrafive]

Try pulling all the relays from the fuse boards.

If you can turn the key to ON without blowing the fuse, you know one of the relays is part of the circuit with the short.

If the fuse doe not blow, install relays one at a time until the fuse blows. then that is the circuit to investigate.

If the fuse blows with the relays out, it could be a short between the switch and relay so they can not be ruled out. Check the power wire to the relay and ground to see if it is shorted. Do this with an OHM meter and no power on the circuit.

 

[Conn]

There are two "sensors" in the thermostat housing. Both have two wires each and a connector. Unplug the one with the largest gauge wires and re-install the fuse. I think they're 10 gauge.

 

[KB9UDE]

We had a very similar problem with our JD 8300 tractor that was pulling our 1000 bushel grain cart last fall. It turned out that a connector going into the "brain" computer had dirt all around it and shorted something. We cleaned all those connections after blowing multiple fuses and never had a problem since.

 

[Kyle_in_Tex]

Yes, the coolant sensor is likely the culprit. Just unplug it. It is there to adjust for cold weather starts I believe.