I have a 1984 20th Ann Mustang 5.0. And the dash lights don't work. I have found that fuse #13 blows every time I pull the headlight dimmer switch. Either with a 5amp 10amp or 15amp. When I put a 30 amp in.... The lights do show up but then after like 5 seconds fuse #4 will blow(20amp). Both #4 and #13 power the instrument cluster. What would cause this to happen. And I do have an aftermarket radio in if that matters. Other than that everything is stock.

 

Well, not being able to "see" it, I assume that the stereo works? If so, I would look for a short possibly in the taillights?

 

you need to look at wiring diagram and try and determine the most logical place to start, i don't think you would have a n issue in the taillight circuit, it will be on a different fuse than the dash lights, i would look for things like the obvious is there any after market equipment tied into that circuit, radio lights, gauges and the like.................ps the last thing you want to do is put in a bigger fuse!!

 

yeah the fuse was only to test something for a quick couple seconds.

by the way i'm gt350dad's son and its my car.

 

i would suggest using a 15a cycling circuit breaker if you are going to do any testing

 

Found the Problem.. The person that hooked up the radio I guess decided to wire fuse #13 to the radio's ground. So I just cut it and put electrical tape on the ends.

 

Blowing fuses is usually a result of either electrical shorts, or excessive voltage/current in the system. That's what the fuse is for after all, to prevent the system from overheating and starting an electrical fire.