So quick question. I was installing a new head unit in my 99 and it was not turning on. I hadn't crept the wires just twisted them together. I wanted to check the stock head unit so as I was pulling the new head unit i forgot to turn of the key. One spark traveled from the yellow wire but I didn't think much of it. I replaced the stock head unit and it didn't turn on either. After checking the fuse I had blown the 29th fuse so I replaced that and then still didn't turn on. Any ideas?

 

Welcome to the forum

Just a heads up
When working on vehicle electrics you unhook the Battery, many components have power when key is OFF, radio is one of them
And many wires have power so can short out by you moving them around to get to other wires.
The "yellow wire" has power key on or off

Go here and look up your year's Radio wiring diagram: Ford Ranger Radio Wiring Diagram

Looks like there are 3 fuses used in 1999, + dash light power to the Radio