short to ground?79 Bonneville..
 

79 Bonne,was fine when I parked it LOL...Been driving my 97 T/A convertible so the Bonne has been sitting a while...Drove it last week and wondered why people got on my ass when I hit the brakes...Asked my friend to see if I had brake lights when I hit the pedal. NO..... fuse was good, had power to rear plug,BUT when plugged in nothing to the other side of the harness plug????Been driving me insane for a few days now.replaced the turn sig switch thinking it had something to do with it..Nope..So after pulling on the harness and other stuff,I now have brake lights BUT the fuse gets super hot but won't pop no matter what amp fuse I use...So I give up,have brake lights now,but will have to put in park at stop lights,,the fuse gets so hot,I don't want the car to go up in flames...any thoughts??? It is a little rusty,water gets in the front at the windshield. Vinyl top car ..:noidea::mad:

If you have normal power to the rear plug until it's plugged in, I'd expect the problem to be downstream of the plug somewhere. That is, nearer to the light socket harness... IF I'm understanding you correctly that is..
If that's the case, unplug it and check the tail light harness resistance to ground.

I did and no problems with it.

and I have a factory manual with wire diagrams.

Do you have good clean contacts on both sides of the fuse? You could be building up resistance right there at the fuse. resistance will = heat.

No,will clean tomorrow and see.

I work on school buses and all other vehicles.

One thing I've learned on, (vice grip terminology). Continuity can be an elusive thing in ANY wiring connection, large or small. Sometimes small wiring connections like your tail/stop/turn lights can look fine. But a film of some sorts builds in the connection. Over time it can stop the electricity flow. Simple connections cannot be taken for granted..

I deal with this stuff every day.

Do the light sockets form the ground for the circuit when plugged in? If so I would run a separate ground wire from the socket to a good ground in the trunk and see what happens. Those old twist in light sockets lose the ground very easily.
My old 69 GTO used to only have "front" brake lights due to the rear sockets not having a good ground. The brake lights would actually light up the front turn signal bulbs when I pressed the bake pedal. Add a good ground solved the issue.

Good luck!

Send a PM to "Electrical George" (George Kujanski) and ask him.



A real wizard he is.

check the trunk harness where it travels thru the dropoff. I've seen a bunch of GM cars of that era have a short in the harness there.

So I pretty much got everything working,but the fuse still gets a hot.I bought all new fuses and used spray cleaner on the fuse block..I don't drive it much but still need brake lights ..Even down here in crazy land [Florida] LOL

It still seems to me that if you unplug part of the harness and it doesn't get hot anymore the problem is likely downstream in the part that you just unplugged. That's not to say that the harness is bad but whatever is bad is probably in that harness or connected to it.

Pull every trunk tail light socket and pull the bulbs. Hit the brakes. Does it still get hot? If so, problem in the harness wiring. If not, problem in one of the sockets\bulbs - add bulbs one at a time until the offender is found and repair.

It's getting hot because of excessive current and will eventually blow. I've had problems like this on several cars - once was because of a bad socket that had a ton of corrosion on it (none of the others did) and another time was because one of the rubber boots that the wires pass through sheet metal on had worn\failed and rubbed the insulation away on a wire. The worn insulation was an intermittent problem that happened more when you turned right than left which made it all sorts of fun to find.

What Ben says. Make sure the taillight bulbs are correct, i.e. not a single contact base. Should have a two-contact base if it's a combo brake/taillight.

George

I would look under the sill plates, if I remember correctly the wires to the rear brake lights run under the drivers sill plate. You probably have a hot wire grounding out there.

all new bulbs

did that,no problems there

Fuse get's hot but does not blow? I see you have tried lower amp fuse, so amperage going thru is not excessive to blow the fuse. I would suspect bad connection in fuse box
either at fuse holder it self or on backside of fuse block. High resistance causes heat. Try sanding or wire brushing the fuse holder terminals. With battery unhooked first.
But possibly the terminals in fuse box that supply power to the brake lamp fuse could be corroded due to water leak?? Just a thought.

did all that also,and pulled the fuse box and cleaned behind tried to clean each plug for fuses.,no corrosion seen ,and yes water leak. vinyl top roof rotted under it,,leaks front and rear glass..going to put a cover over the fuse box to try and keep it dry.