You say the brake lights come on before the fuse blows? My first step would be to verify the bulb sockets and housings are not corroded or have broken wires. Fuses blow because of high current and unless you've changed something (like adding a trailer harness is one common change) you have to track down why the current is higher than Toyota intended. Rust and corrosion on wires, connections and contacts is 99.999% of the time the reason.
Rust has a much, much higher resistance than clean copper or steel. If I had to guess years of mag chloride and moisture have changed the copper in the connections into nasty, green messes. Pull off the connectors throughout the circuit and see, could be in the housing or anywhere between the pedal or anywhere. A service manual would be handy, it's possible the harness is not all that simple as a point-to-point and probably gets bundled into a couple of big connectors under the dash.
In Cruisers this happens because the housing itself is rusting in the rear frame member and that might be the problem here, but it's less likely because harnesses now contain the circuit return since stuff is made from plastic and doesn't ground through the housing itself.
'91 Toyota Pickup
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29
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