Hi, everyone. I hope I am posting to the right place. I admit I am not a frequent visitor here but need some guidance on a wiring issue on my 69 convertible. Several years ago I replace the entire wiring system with an American Autowire complete set front to back. Everything worked like a charm until recently. As I was backing out of the garage my wife informed me that the left side rear brake light wasn't working so I checked all the lights in the back. Everything seems to be working except for the left turn signal and left brake light. Taillights are fine, dashboard turn signal indicators work fine, right side works fine. Left side does not. I thought it was just a bulb issue but I replace everything with 1157 dual filiment bulbs. That didn't solve the issue. Any ideas for all you experienced electrical guys?

Pull the socket out, remove the bulb. turn you emergency flashers on, the use the same bright filament that your brake light and turn signal use. Check voltage at the buttons in the bottom of the socket. One is for tail lights, it should be dead. The other is for the bright filament. it should be pulsing with voltage. Remember to ground the negative lead the the chassis. The two wires feeding the socket are the positive voltage to the two filaments, not a positive and negative.
Both filaments use the same ground through the plug. If your tail lights work, its not the negative side. If the voltage is not pulsing when you test it, trace the wire. That would be your problem.

Thanks for your suggestion. It confirmed that the right side pulsed on the one contact point and no reading on the other. The left side where the problem resides got no reactiion to either contact point in the plug. Since the issue is with the brake lights (both bulbs on the left side) and the turn signals (both bulbs on the left side) while the brake headlights work, I assume it is just the one wire feeding the second contact point that I should trace back. Does that sound right?

yup. Wish I knew the wiring better, I could tell you where to go next. You might take a look at the schematic and see where it comes from. Might be under the dash somewhere.