Modern Vespa

Kill switch works
Horn was working (for a bit )
Vespa starts and runs

But the lights all seem a bit random and I'm not sure if they're wired up correctly?

I'm running a SIP loom 12v AC, no battery, no indicators and a SIP Vape.

So at the front is two bulbs:
Small light (its own bulb),
Main dipped beam, full beam / brights (two functions of the same larger bulb).

The light switch is the Grabor conversion to work with the 12v AC.

Any tips on what I've done wrong?

edit002: see FridayMatinee's post below, I believe is correct!!!

Other than the extra yellow running light wire the headlight wiring is same as mine. But the switch wiring is definitely different than how mine is wired (SIP vape with battery). I was able to snap a couple pics you can use for reference, hope it helps.

edit: I'm guessing...that the grey wire goes with green, yellow goes where grey wire is in your pic

You've got a bad ground somewhere is my guess.

Did you run a second ground from the CDI to the engine case? And did you double ground the regulator/rectifier (whatever that thing is called).

Side question. Where is that second yellow wire going in the headlight pic? Got once attached to the pilot bulb but where's the second one?

the grounds!!! I agree with FM and hadn't considered that. I did see weird 'consequences' when one of the ground wires got loose while testing a new turn signal wiring setup.

Make sure you tap a screw onto the regulator for a ground to the frame. If you haven't already and definitely run a second ground from the cdi to the frame. I also had issues with the lights not working and once I did that all was fine.

Thanks for all your help!

I do get lights, but I seem to get everything in one switch position but not the parking / small light on its own. I'm also not sure if I'm getting brights / beams as well as dipped regular headlight. In one switch position, both bulbs light up.

One of the yellow cables is attached to the green light on the top of the headset but I've noticed this doesn't have a bulb so will swap this second yellow cable to the speedo.

The grounds at the back of the Vespa are solid, but at the front I've got two ground cables to attach and I've put these both together to the metal bracket inside the headset?

I'll move the yellow wires at the switch to match yours buongiorno. I think the grey wire is the supply to the switch but I'm not sure?

You might also want to take another look at the dark green wire circled in my screen grab...it looks like you have a loose strand.

Thank you for pointing that out jonmonts! I didn't think it was an issue until I saw the magnified shot you posted. Another item to put on the todo list. Appreciate the feedback!!!


JakeM - the pics I posted is a 1979 primavera et3 smallframe. A multimeter helps a lot, I was glad I got one for my turn signal project.
I can't tell what the grey wire on your switch is for. The Vespa wiring diagrams are confusing and I'm still learning. What I think...on my switch the yellow wires are for the running/parking lights, one provides power while the other goes to parking light bulb. I think it also powers low/hi beams from switch but not sure. The white wire provides power to the switch for the horn, I'm not sure what else it powers if anything. The white wire is what I've tapped for the new turn signal lights and switches.
Headlight - If you connect that second yellow wire from the headlight to a bulb or speedo, make sure that is also properly grounded.
Good luck, wiring issues can drive one mad!