Hi I'm a new member and truck owner. I have recently gotten a 1990 ford ranger, 4 cylinder. I have experience working with vehicle but this is my first vehicle to own, because I'm 18...

Recentally I had installed a new head light switch because the old one was faulty. Before installing the new one my dash light weren't working, I noticed the fuse was blown so I replaced it with the proper fuse. Every time I switch on the running light "also running the dash" the dash fuse would blow... I'm positive it's a fault in wiring but I don't know......

Daniel, welcome to FRF. Does the truck have the stock factory radio or has it been replaced with an aftermarket radio?. If the radio has been replaced check the wiring behind the radio & make sure the radio ground is attached to a body ground. I used to see people mistake the wires for the when hooking power & ground hooking the ground wire to the radio light wire & when you turn on the lights it blows the dash light fuse.

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2000 Ranger Extd Cab XLT, 4X4 Off Road, 4.0L, Auto, 8.8 - 4.10's, 01 grille & lights swap.
69 Mustang, modified 5.0, & 5spd.(project)
99 Explorer Sport, 4.0 SOHC, Auto, 8.8 - 4.10's, PW, PL, PM, Cruise, Tilt. (Wife's DD)
05 F-150 2WD Regular Cab. ( My DD)