Now my tail lights flicker

Question:

I have an electrical issue with my 1956 Chevrolet Bel Air. The tail lights flicker when I press on the brake pedal after a period of a few minutes. I think I know the cause, but I want to run it by some other folks.

With the light switch cluster from the dashboard removed I can see the breakers opening and closing rapidly. It seems like too much current is going through the breaker. This happens with or without the headlights on. So to me it would appear the more current going through the switch, the quicker the flickering starts. This used to happen with my headlights. I solved this by putting in relays going to both lights.

I noticed my tail lights flickering when I fixed my dashboard lights recently. As a result, my dash lights work (speedometer, radio, and tach) and my tail lights now flicker. They only seem to flicker when I push on the brake lights, with or without the driving lights (or parking) lights on.

Funny thing is, the problem never occurred on my tail lights when my dash lights were not working. Now when I disconnect my dash lights, the problem is still there. Also, I attempted to fix this by putting in a relay to my dash lights. I’m not sure if this is associated with the problem or not, or just bad timing. I think it’s a poorly designed switch, but it’s the third switch I have tried. Could there be a short somewhere? I don’t think so. Any ideas are appreciated.

Answer:

The flickering lights are probably due to a short circuit somewhere in one or more of the car’s lighting circuits, with said short causing the circuit breaker to vibrate.

Systematically disconnect the lighting circuits in your car until the flickering stops. Once it stops you have identified the circuit(s) that have a problem with a short.

Another possible cause of the flickering is a bad voltage regulator. If the regulator is causing the continuous pulsation in voltage then all of your lights will flicker.