John Deere GX 345 Blows No.1 15 amp fuse when brake is depressed HELP...........

[beswart]

Mowed the lawn, got off the machine, when I got back on it would not start. Checked fused and top fuse was blown. Replaced, turned key on and everythings fine until I depress the brake. Fuse blows. Can a bad brake switch cause this or might it be deeper? Thanks in advance for your comments. Bruce

 

[beenthere]

To find the cause of the blown fuse, wire in a 12v bulb (I use a bulb socket with couple pig tails) and solder the wires to a blown fuse. Stick this in the fuse holder and when the short happens, the bulb will light.
Makes tracking down the culprit easier (and less expensive than replacing a fuse each time).

 

[k0ua]

To find the cause of the blown fuse, wire in a 12v bulb (I use a bulb socket with couple pig tails) and solder the wires to a blown fuse. Stick this in the fuse holder and when the short happens, the bulb will light.
Makes tracking down the culprit easier (and less expensive than replacing a fuse each time).

That is a very useful diagnostic tool. Here is what to look for.
Find the brake switch (after wiring up the above mentioned diagnostic tool) And make sure when you press the brake pedal the light lights brightly.
Now find the brake switch and pull off the load side wiring to this switch. Use your voltmeter or test light to find the hot side and the load side.. This is provided the brake switch actually switches + 12 volts and not actually switches ground and the +12 goes to the lamps first.

But say it does switch the +12 volts:. Now with the load wiring and bulbs pulled off press the brake switch, and I bet the diagnostic tool lamp will not illuminate.

Hmmmm What could it be. Well it could be the load wiring rubbed thru the insulation. or it could be a defective socket, or even a defective bulb.. Yes there is such a thing as a shorted bulb. corroded shorted socket. or shorted to frame (negative side of battery of course) wiring.. just gotta eliminate each one. Like beenthere said, with his diagnostic tool idea.. sure beats buying and blowing a handful of fuses.

 

[beswart]

That is a very useful diagnostic tool. Here is what to look for.
Find the brake switch (after wiring up the above mentioned diagnostic tool) And make sure when you press the brake pedal the light lights brightly.
Now find the brake switch and pull off the load side wiring to this switch. Use your voltmeter or test light to find the hot side and the load side.. This is provided the brake switch actually switches + 12 volts and not actually switches ground and the +12 goes to the lamps first.

But say it does switch the +12 volts:. Now with the load wiring and bulbs pulled off press the brake switch, and I bet the diagnostic tool lamp will not illuminate.

Hmmmm What could it be. Well it could be the load wiring rubbed thru the insulation. or it could be a defective socket, or even a defective bulb.. Yes there is such a thing as a shorted bulb. corroded shorted socket. or shorted to frame (negative side of battery of course) wiring.. just gotta eliminate each one. Like beenthere said, with his diagnostic tool idea.. sure beats buying and blowing a handful of fuses.

I've been using a test light that resembles an ice pick with the element in the handle. Not sure about the load side of the brake switch, I removed the switch and it only has two terminals. I checked the continuity of the brake switch and the multimeter went crazy throwing all sorts of numbers on the screen. Thanks to you and beenthere for the ideas.