Lights stay on - mud in fuse box

[herbenus]

Last weekend I was on tractor when I noticed the lights were on. Switch was off. I turned switch several times and turned ignition key on and off and even put key in and out. Lights stayed on. I finally pulled fuse for obvious reasons. (Lights went off with fuse pulled.) When I opened door to fuse box there were lots of blobs of dried mud all over fuses. Since it's been really wet lately I can understand how mud could get up there, although I was surprised. I tried to leave tractor parked but sometimes you have work to do.

I'm hoping this is where I have a short but it might be somewhere else. I'll find out. And I don't suspect dried mud carries much current so it probably is somewhere else.

Question is: Any suggestions for cleaning out fusebox? I figured WD-40 or silicone spray and a toothbrush for stubborn spots. Or maybe even a contact cleaner, followed by silicone spray.

Any suggestions for where to look for short? If not in fusebox I was going to pull switch.

[normde2001]

I would unplug the battery, spray and brush on an engine cleaner/degreaser like "Gunk", hose it down and let it dry or blow dry with compressor if available, then, if still shorted, get after it with a volt/ohm meter.

[Anonymous Poster]

Cleaning with the Gunk stuff should be ok, but after it is dried out I would spray with WD40 to prevent corrosion. Don't use brake cleaner or harsh solvents like that. Could be bad on plastics and wire insulation.

[herbenus]

Although I'm not crazy about the thought of hosing down fusebox, it's already had a mudbath so what's a little more. Good tip on disconnecting battery. If using WD-40 (no water), I probably would have left battery connected, and shorted something with a cleaning tool. And I don't have a compressor, but I do have a good leaf blower, a nine-year-old, and earmuffs.

[BB_TX]

I agree with you that the mud is not likely carrying enough current to turn the lights on.
But I am curious. Was it mud thrown up by the tires? Or was it maybe from dirt (mud) daubers?

[herbenus]

Not mud daubers. Thrown up from tires. Several times in the last few weeks I've been aggressively down to the axles - trenching, pushing tree down, and I've got a muddy spot I've had to carry gravel across for a pad. But I really don't know when mud got in. I haven't looked in fusebox in probably a year or more. Last I looked it was just real dusty. I guess I need to be more conscientious of housekeeping. And I know engine is due a cleaning.

Mind you, fuse box is not covered in mud. But there are 5 or 6 spots of mud, about 1/2" across, plus some smaller droplets. These are on fuses and fuse holdersl. You'd think it would be better protected or even sealed.

[rdbrumfield]

Even with a short in the fuse box the only way the lights will have power is through the switch. I would check the switch out for the short.

[herbenus]

Agreed. I'll probably clean up switch at same time as fusebox and if problem is solved I'm done.

[normde2001]

While the mud was wet, it could have shorted across a fiber, plastic, or rubber insulator and caused it to carbonize, thereby causing a permanent short after it dried. Possibly cleaning may reveal a carbonized insulator or something like that. Carbon makes a great conductor.

[Anonymous Poster]

I agree with rdbrumfield on this one. I can't see how a short in the fuse block can cause the light to stay on. If it's not a defective switch, I would examine your wiring harness. I'll bet a wire has been rubbing on the frame somewhere and finally wore through the insulation.

John