2007 Columbia blowing fuses when brakes applied

Just to clarify whitch fuses? And have you checked grounds?

 

If you are certain it is not any of the light assemblies/bulbs and can not find fault with wiring, then I suspect the switch is shorting.

 

Ditto on the switch and look for a faulty ground

 

Ground wires can come in contact with about anything other than a power circuit, in fact many grounds are not insulated at all, usually large grounds such as that connecting the chassis to the engine block, etc., however, being exposed makes them susceptible to corrosion. if they are insulated and showing chaffing, I would replace or cover them in order to head off failure down the road.

 

Yes fix any wireing that is showing wear. The switch is located on the pedal arm.

 

Do you use the same trailer or do you use multiple trailers? If the fuse is blowing with the same trailer connected, it could be a bad ground or short in the trailer wiring causing it to eventually blow your fuse on your tractor.