Lately I've been having a problem with the fuse that powers the dash lights and the tail lights. I have to replace the fuse every two weeks. I was driving up the road recently and that fuse went out and right after that the horn started honking. I pulled over to look at it I noticed my headlights were on. So I went to turn them off and when I did the horn shut off but the headlights didn't. After I did that the horn wasn't honking anymore so I drove home. When I got there and parked and shut the car and the headlights off, the headlights were still on. I pulled the horn relay and the light relay and they both shut off. I also pulled off the battery cables. What could have caused this, and how can I fix it? Thank you for your time.
My car has 210357 miles.
My car has an automatic transmission.
It sounds like you have a rubbed through wiring harness or two. All the components you mentioned are switched on the ground side. That means if there is a short to ground on the switch side before the relay, then the light will turn on. This would lead me to think that there is a rubbed through harness in the steering column. This will not blow a fuse though.
The light or horn will simply turn on without you moving the switch. The fuse for the taillights and dash lights is a different concern. A short to ground on the positive side, after the relay will blow a fuse. It will only blow the fuse when it is switched on. This could mean a short in any positive wire in the taillight circuit. There are a lot. Every switch that illuminates when you turn your parking lights on could be shorted. Any taillight or parking light circuit, too.
Here are some tips. There is only one way to find this type of problem - it will have to be visually traced. Follow the harnesses with your eyes and look for damage. Use the clues that the car is giving you to narrow your search. The wires will need to repaired after the problem is found. If you need help having this diagnosed and repaired, a certified technician from YourMechanic can inspect your electrical system and let you know what fixes need to be performed.