Tail light Wiring California III

[Turin]

I'm probably overthinking this.  The harness from the Cal III has 4 wires. 2 black (ground) 1 yellow ( running light), and one red/blue ( brake light).

The taillight I want to use has two wires. I can run all the grounds together... can I run the running and brake lights to the one power wire on the new lamp?

Thanks!

[John A]

I usually just swap the socket and pigtail to a dual filament. Some lights are easy, some take a little modification. If you can find the right socket, there are many styles , it helps. I don’t know if you can hook the two together , I never tried that. https://www.autozone.com/power-tools/electrical-socket/p/dorman-conduct-tite-tail-light-socket/600544_0_0  or similar

[Turin]

I opened the light and found two bulbs! the black wire goes to the bottom bulb, and the green goes to top. I suspect I'll need to run a ground to the bracket.

I also could be very wrong. Spent a few hours scratching my head.

[John A]

I opened the light and found two bulbs! the black wire goes to the bottom bulb, and the green goes to top. I suspect I'll need to run a ground to the bracket.

I also could be very wrong. Spent a few hours scratching my head.

That sounds right!

[Turin]

Go figure that on a Ford Model A tail light, the running light wire is black and the brake light wire is green. I'm so used to black beaing a ground that I didn't think. I ran the guzzi ground wires to the stainless bracket.

Thanks John, sometimes I need a sounding board to figure sh!t.