Ok hear it goes have a costom bed on my 06 now has 6ea red running lights in back 7ea. 2" round marker lights keeps blowing 15 amp fuse anyone see a problem with going to a 20 amp fuse, checked for short and everthing looks ok in wiring.

 

The problem with adding a larger fuse is the wire size in that circuit might not be able to handle the load. A fire could result.

If it were me, I'd add a relay to power the lights on the bed. This will require an inline fuse somewhere near the battery, the relay, and then a wire run back to the bed and a wire run to the original running light(s) to fire the relay.

If you go this route, search for "how to wire a relay" on the internet.

 

He is correct. As an electrician, I always use this expanation to customers who like to do the same thing. The whole point of fuses, autos or buildings, is to protect the wires- period. If you substitute them for other than what was designed/intended, you might as well not have one. Under too much current, the insulation can breake down causing future problems, the copper may heat up and cause fire, and a short due to either will leave you without something somewhere.

I know it's convenient, and seems to work with no visual issues, but try to resist. The correct solution would be to run a new circuit or rewire with larger wire.

 

check the wattage on the new light, try to match w/factory wattage you might be drawin' to much power, that might give ya an over load. make sure you have good grounds. try LED lights, there briter, they take nothin' to run and they almost never blow.