When brakes are applied, fuse is blown. Have replaced fuse several times. Also, running lights dim before fuse blows.
There is a short to ground after the brake switch connection. Look for a damaged wire to the brake lights.
In a car this age ;
- clean corrosion fron inside every bulb socket. Don’t try to figure out which is the culprit just start cleaning.
Take out each bulb and you’ll probably see rusty corossion down in the socket. Clean under the contact plate too. - Follow all the wires looking for age cracking in the shielding thence possible grounding out.
- may also be the brake light switch shorting from age accumulated gunk and corrosion.
In all honesty, in a vehicle this age with a wiring problem it’s usually easier and more permanent to just string new wires.
You might try disconnecting the line on the downside of the brake light switch, but leave the hot side of the switch connected. If the fuse still blows, the brake light switch may be shorting to the chassis and needs to be replaced. I had this problem in a 1947 Pontiac and replacing the brake light switch cured the problem–it was shorting to ground. If the fuse doesn’t blow, then you will have to trace the wires further. One place to look is to see if the brake pedal lever is mashing a wire when you press the brakes and causing the short.