How did the factory separate the turn signals and stop lights but run wires to the rear that share these functions? In other words, what keeps both lights from blinking when the turn signals are used but both tail lights burn when the brakes are applied? On a 60's Impala, the magic separation seems to occur in the steering column. Thanks
The turn signal switch has six wires. One is power from the brake light switch. One is power from the flasher can (blinking power). Two go to the front lights (one right, one left). Two go to the rear lights (one right, one left). When the switch is in the center position, the blinker power goes nowhere. The brake light power connects to each of the rear lights. When the switch is to one side, that side gets blinker power to the front and rear lights. The other rear light still gets brake switch power.
Squirrel is dead on correct. Also the dash indicators power come from the Front signal terminals in Factory units. I decided a long time ago it was more important to me to know my Brake lights work as well as my blinkers were working. I have been connecting my Dash indicators to the rear bulbs for years so my Dash indicators work with both the Brake lights and signals. It's a simple 2 wire change over. Ya, I know. I don't do things like Normal People. The Wizzard
Thank you HAMB'rs, very quick responses and technically informative! Do aftermarket wiring kits use these same principles?
Yes, aftermarket wiring kits work the same way. It can get fun figuring out which wire goes to which terminal on the switch, since the switches have different colors on different make cars, and on aftermarket switches. Also GM changed the color code on their switches in the early 60s... https://www.jalopyjournal.com/forum/threads/tech-gm-turn-signal-wire-colors.124217/
We did (& still do) things a bit different down under. Law says the rear indicators have to be orange, separate from the tail & brake lights, so we have separate circuits for tail, brake & indicators. No magic required. Although I think maybe in the early days (50's- 60's) before indicators were compulsory we did it your way. Ford used to use the orange indicators as reverse lights. They had a diode steering block to drive both rear indicators from the reverse switch on the gearbox. Is that what happens stateside?
here, reverse lights (back up lights) were always a separate circuit, white lenses and bulbs, wired direct to a switch on the transmission or shifter. They were optional until 1966, then they were required on all cars and trucks. In the early days of add on turn signals, it was pretty common on trucks to use a 3 wire switch, and add another light to the front and rear to work with it. We started getting some of the separate orange turn indicators on import cars in the 1960s, and some US cars got them in the later 70s, iirc.
It won't check if the brake light bulbs work, but it will check if the switch works...if you're using a hydraulic brake light switch, prone to failure, it could be helpful. you could also add fiber optic displays to check the bulbs, like Vettes had for a while
Squirrel is correct again. However watching your reflections on the Vehicle behind you is another way to be sure bulb is good. That works better at night. Inside the garage against the door also works.What got me started way back was a tempermental column switch that didn't always make good contact internally. I just learned yesterday at our Club's 65th anniversary party that just last Friday night one of our Guys got rearended in his finished for just 3 weeks 37 Studebaker Coupe Express. He was stopped on a 2 lane road turning Left. Damn sad deal, truck is a Total and He now has a broken back. I'll get photo's latter this week. You only need to get rearended once to become Anial about brake lights. So brake indicators in the dash does 2 things, tells ya the switch is getting power and that the switch is working. The Wizzard
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