The fuse was not blown but the plastic had melted

A reader describes what can happen when a loose connection causes a high resistance which in turn generates sufficient heat to melt the plastic on a fuse.

My wife's 89 Celica GT had a problem with the brake lights not working. The first thing I did was to check the fuse. I found the plastic on the blade type fuse to be melted but the fuse itself was not blown. Went to Toyota dealer after I could not solve the problem myself [I am an aircraft mechanic but I try to stay away from cars as I don't always have the patience or the manuals]. The Toyota dealer couldn't find anything wrong since the lights started to work after the mechanic played with the fuse. So $80 later I took the car home and found that all it was was the fuse was loose in the fuse holder. The fuse had gotten so hot that it melted the fuse holder and the plastic on the fuse without blowing the fuse. The burned fuse holder caused a high resistance in the brake light circuit not allowing the lights to work. To bad there $80 mechanic couldn't find this out. I bent the blades out on the fuse and everything works great.

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