25 amp fuse continues to blow neither horn nor lighter works. Am I correct in assuming must be a short? Where do I start in dealing with this problem. Any advice would be appreciated.

 

Could be that either the horns or the lighter socket are shorted. Look for coins in the lighter socket, I've seen this happen a few times. Otherwisw, get a schematic drawing of your car. Locate the fuse on the drawing and find out what color wires are connected to it. Follow the wires to where they are going and look for cuts, shorts, grounds, etc.

 

I had this problem as well, turns out my lighter had just died. I solved it by removing the lighter and it's face plate. When that was out unplug the lighter from it's power source and replace the fuse. That should bring the horn back into play, then just go to the auto parts and get a standard cigarette lighter and replace the old one, plug the power source onto the new one and put the face plate back on. Whole problem should be gone.