Today my 86 Fiero started to honk the horn randomly. Eventually, the horn stayed on. I wiggled parts on the fuse board around and it stopped. Next I noticed a vibrating from a relay underneath the passenger dash. It wouldn't make the noise when the doors were open and my radio was going on and off. I looked at it and the bottom was busted out. I took it to O'Reilly's and they said it was the horn relay. Okay, that explains the horn, I thought. I switched it out and noticed my battery fuse had blown. This explains the radio. I then switched it for another fuse and it blew immediately. Then I tried again and it was fine... until I turned the car on. I got a buzzing noise from the relay I had replaced until the battery fuse blew again and the buzzing stopped.
Any ideas as to what is happening? Did they give me the wrong relay? Is my fuse the wrong size? (25A is what was in there).
Years ago my shop was looking for reason why the horn would blow the fuse on a chev pickup truck. We finally traced it to a splice under the dash in the harness that connected the horn fuse and lighter fuse to power up the lighter and horn. The engineers made the wires undersized. It turned out the cigarette lighter has semi melted and was shorting out the plug somewhat causing a drain. Disconnect your lighter and try the horn again. This sounds sooooo familiar.
Yeah the radio and cig lighter fuse are the same circut, (hold down the cig lighter, the fuse blows, the radio quits and usally the brake light will come on, as then it is back feeding a circut) just an fyi