VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Brake lights keep blowing fuses

I have a 33 Master Coupe. It keeps blowing 10 amp brake light fuses. It seems like if anything metal touches the outside of the brake light switch the fuse will blow. It doesn't make sense because the switch itself is attached with a bolt and is grounded. I have taken the switch apart and everything looks good inside. It doesn't look like anything inside the switch could short out against the casing.

Dennis

Look for a direct short in other areas of the lighting circuit.

One place to look - inside the tail light sockets. If there are any particles of rust in them, they could be a cause of the line (hence fuse) shorting. Another place might be the directional signals switch (if you have signals). I kept blowing fuses in the tail light circuit on a car I once owned (not GM) and out of frustration trying to find it, replaced the fuse with a piece of tinfoil. When the smoke started coming up out of the steering column I knew I had found it. It was the signals switch.

kaygee…..Hmm, I think I'll save the tin foil trick for the last resort. The tail light sockets with rust is a good idea. I wouldn't have thought of that. Thanks.

Dennis

I agree with JYD, look for a bare wire between the switch and the tail light or in the tail light.

Try installing another fuse. Get to the light harness to the rear light(s) and hold the wire. Have someone mash the brakes, It will get warm - hot before it blows the fuse.

I once traced the same trouble out on a 41 that would blow a fuse every time I turned the lights on. It was a frayed wire going to the left tail light in the trunk. This was back in the seventies when I was driving the project 41Hudson, IL to NC . Had to search it out at a gas station in TN. I blew several fuses before I discovered the short.

I only found it owing to superior mechanical and electronic skills. Yeah, right!

Good luck with finding the trouble,

Best,

Charlie

So here is what I have found and I don't understand it, but the brakes lights are working now since I did the following last night. About a year ago I installed a 6 volt alternator from 5th Avenue Garage. It's a two wire alternator. I hooked up the exciter (yellow) wire to the stop light switch so it would turn on when I turned on the ignition switch. It always worked fine until now. I'm not sure why I thought of this, but last night I unhooked the alternator wire from the stop light switch and hooked it up to the ignition side of the coil. Now the brake lights work fine. I called 5th Avenue today and discussed it with them. They told me I don't need a fuse in that yellow wire because its a low voltage wire. It seems to me like I should put a fuse in it. I am wondering what size fuse it should be. It looks like a 16 gauge wire. 5th Avenue has never heard of it blowing the brake light fuse when hooked up like this.
I don't understand why it was blowing the brake light fuse. Does anyone have any thoughts on this?

Dennis