Lights blowing fuse

Kccca · Feb 25, 2017

Lights were not working on 2-105 White when we bought it last summer. It's a 1976 w/ cab. Weather pretty for this time of year, so I parked it in front of the shop and started to try to find the cause of the malfunctioning lights. It had the old tube type fuses and when I put in a new fuse and turned on the lights, it would blow the fuseso I purchased a blade type fuse holder and wired it into the system....blows fuses. Out of curiosity
, I turned the light switch to 'dim' and put the fuse in, and the lights came on. Turned switch to 'field' and blew fuse. Got a short in the high beam wiring or the switch. How do I find out where the short is?

D beatty · Feb 26, 2017

Go to back of switch and find the high beam wire and disconnect it and make up a wire with test light and hook it up. Then turn lights on high side and if it blows fuse it's in the switch if it doesn't your going to have to trace wires for the short or run new wires to lights.

jeffcat · Feb 26, 2017

Just bet you find a "pinch" or a rub through some where. Do you have the wiring harness for this thing? If you do and there are terminal blocks do the old 50% of the way back deal. Unhook a wire and see what happens. I know on some of the older tractors I have worked on, there are terminal blocks where a supply wire branches out in both directions. Unplug on at a time. Good idea.....take the hood off and start looking over the wires. Bet one is pinched under a bolt or metal pannel. Watch out for the old letting the smoke out of the wire harness! !!!!

Russ from MN · Feb 26, 2017

Take the fuse out, and hook a test light in series in place of the fuse, when you turn the lights on bright the test light should come on bright. Then start checking the wires, when you find the grounded spot the test light should dim.

Geo-TH,In · Feb 26, 2017

I have an old DC ammeter. I use it in place of the fuse, so I can see when the short occurs instead of replacing blown fuses.

If nothing else you look for the smoke to find the short. The wire will get hot right up to the point where it's shorted. Better have a fire extinguisher handy.

Some place the hi beam wire is touching ground.
Good luck finding it.

notjustair · Feb 26, 2017

I just replaced the switch on my 886 because of that. It was fine with the road lights on but when you turned on the field lights it sometimes blew fuses. There was no rhyme or reason, but that sure makes it interesting spreading fertilizer at night in a field full of oil wells. Then it became constant. I pulled the switch and used a jumper wire to connect the fuse side to the field wires and they came on just fine. That's how I narrowed it down.

In case the field lights overloaded it, when I put in the new switch I put the field lights on a 40 amp relay. She's worked just fine since.

Goose · Feb 26, 2017

You probably have a shorted wire somewhere.

I once had a short in the wiring harness going to the alternator on an 856 Farmall. I took the easy way out. Instead of tearing the harness apart, I simply ran another wire bypassing the area where the short was and solved the problem. I did a neat enough job so it wasn't obvious.

Janicholson · Feb 26, 2017

Google automotive short detector. I have used mine 50 times and it found the short 50 times. Pinched wires, ground and hot melted together, chafed insulation. Jim

john *.?-!.* cub owner · Feb 26, 2017

Have you checked that you are using the correct size fuse? Are the bulbs the original types, or have they been replaced with brighter ones? Once you get the number off the bulb you can google it to see how much current each bulb requires.

Lights blowing fuse

Kccca

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D beatty

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jeffcat

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Russ from MN

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Geo-TH,In

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notjustair

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Goose

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Janicholson

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john .?-!. cub owner

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