'95 ford bronco keeps blowing fuse 13 it did it once i replaced the brake switch and it blew instantly i put the old swith in and it worked for a few days no when i put in a fuse it blows instantly?

Answer 1Fuses [and circuit breakers] are designed, intended, and installed in an electrical ciruit for one purpose, which is to protect the conductor [wire] from damage due to excess flow of current, which can be caused by overloading, or a short circuit to ground.

Unless a fuse is defective from the start, the "blowing" of a fuse is an indication of either an overload condition, or a short somewhere in the circuit.

The occasional fuse blowing described in the earlier stages suggests an intermittent short circuit.

The most recent blowing of each new fuse immediately upon installation indicates that the short circuit has gotten worse, and is no longer intermittent, but complete and continuous.

To continue to replace fuses will do nothing to correct the short circuit.

The proper way to correct the short circuit is to troubleshoot every switch, connector, conductor wire, and device in that circuit.

You will be looking for a cut or pinched wire in which an energized ["hot"] metal wire conductor is in contact with grounded body sheet metal of the vehicle, OR where a hot conductor is in contact with the metal wire of a ground conductor.

If neither of these is present, the probability is suggested that the short is internal to a switch or device.

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That fuse also feeds the notorious 'cruise control cancel switch' which screws into the brake master cylinder under the hood. The diaphragm in the switch will fail, allowing brake fluid to leak into the electrical parts causing a resistive short. So far, you've been lucky that the fuse is blowing, instead of the wiring catching fire. To see if that is your problem, simply unplug the switch and see if the fuse keeps blowing.