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On my 68 the R side brake lights have stopped working every once and awhile they come on but lately only the left ones come on. I have checked the bulbs they look fine. the wire connection at the rear seems okay. Replaced the brake switch but it did not solve the problem. Any thought on what is going on? Probably a separate issue are 2 loose connectors under the dash which I cant figure out how they go together (see pics). I tried sliding one into the other with no success not even sure they go together but I dont see anything else loose that they would go to. Each plastic half has what looks like a thin black wire going into them. Due to the gauge of the wires, I dont think its the cause of my taillight problem. As usual working under the dash is a cramped nightmare very little space to work in upside down and twiste
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FWIW, GM did not use those connectors in a C3. That's almost certainly some aftermarket add on, perhaps for a radio, and they are not best practice to use. Solder and heat shrink are much better, the way NASA does splices going to space.
I did have a brake switch fail on me. But in the debugging, I found that the contacts in the fuse panel had corroded. Cleaning those helped restore some function as well.
While you see those connectors used in many applications, my personal preference is soldering with heat shrink. I have done a number of wire connections and added wires to existing wire / harness on my 73. For the most part, the copper is not very shiny and almost always shows its age. Those “push together crimps” will not clean corrosion off old wires. Even when soldering I usually take some emery cloth and shine the old copper strands, then use some alcohol to clean away any debris. I am one of those old guys who doesn’t like to fix something more than once. For your brake lights, poor grounds and 50 year old bulb sockets are normal culprits. I like to use bulb grease (sparingly) because the old tail light housing are very old. Let us know what you find. You can try a temporary ground with a piece of wire connected to metal and then to the socket ground. Good Luck
You will have to look at a wiring schematic for your model year to see if there is a common ground for the left and right lights. I will guess that both lights on each side have one ground ( stop, turn, back up).
Im good with mechanical fixes but electrical issues are challenging to understand. So I'm trying to think this through systematically. My R brake lights dont work when I press the brakes yet when I turn on the headlights all the rear lights light up. If there was indeed a ground issue wouldn't it prevent the R rear lights from coming when I turn on the headlights as well?
brake light issues
