Hello from finland. I have impala 1965 convertible.Broplem is that my left side BRAKE LIGHT doesn't work. When the turn signal is on at right side, and i push the BRAKE bedal, left BRAKE LIGHT work. Where should i start To solve broplem?
You need to check the grounds (measure the resistance with the OHM meter portion of your multimeter). It will tell you more than just a continuity check. Sounds like one or more bulb's is having difficulty getting a good ground path.
I have had a bunch of grounding issue with my '65. I found taking apart the tail lights and wire brushing the metal bracket where the bulb socket pushes into helps. Also on the bulb socket itself the wire tabs may have to be bent in a little bit. I had the issue where the tabs had lost some of their tension and wasn't allowing the contacts of the bulb to fully reach the contacts in the bottom of the socket.
Because the turn signal and the brakes share the same element in the bulb; if the ground potential of the socket exceeds the resistance of the copper wire and second filament in the other bulb connecting the two bulbs together, the electricity will go through the other bulb and light it up to get to ground if the resistance to ground is too high on the socket where it is being directed. Electricity is like water in that it finds the path of least resistance.
I seriously doubt the problem is with the turn signal as you have initially described the problem.
Welcome to the site from across the pond. I just wanted to 'add 1' for the cleaning of each socket. They're quite finicky and need a good bit of attention. Go for the most common problems first, and that's it. Then on to next items such as wires, connections, and that silly turn-signal contraption in the end of the steering column.
The problem was inside the turn swich. There are somekind of metal plates/springs. When I push them everything works fine. I cleaned them,but the connection is not good. Sometimes left BRAKE LIGHT works some times it doun't.How can i fix it?
You will need to consult your Chevrolet 1965 Full Body Service manual for instructions, though it is also covered in the Fisher Body Service manual for 1965. Another source is a vintage used copy of a 1965 Chilton's Auto Repair book or a Motors Service Repair book for the same year car. These can all be found online.
There should be some NOS switches available if you shop around a little and if you shop a bit, you will find one fairly priced. They are FAR superior to the reproduction switch. As they say, ask me how I know.....