Gleneral wrote: ↑
Tue Jan 28, 2020 9:59 am
...want the exact info about How this is Done on on my 2018 full led teckna. This car has no simple wire to steal the signal from.
I know you never mentioned it, but if you were ever considering it, I'd forget CANbus. Tapping into and then attempting to decode the messages on the CANbus and then trying to make some use of them would be a substantial embedded software engineering project way beyond what you're trying to achieve.
Instead you could find where the fuses are for the headlights and take your signal from there. I couldn't find any info online other than for pre-2018 cars unfortunately, but it wouldn't surprise me if it's quite similar for the 2018 and later models. The PDM (power distribution module) which is located near the 12V battery on the 2017 Leaf has a bunch of fuses on its underside. It unclips and lifts up (dragging a whole thick bunch of leads with it) just far enough that you can turn it over and see the fuses. There's a key to identify the different fuses embossed next to the fuses themselves. Among those, you'll almost certainly find a pair of fuses each for the low beams and the high beams.
To get the signal from there, you could use a piggy-back fuse adaptor like I plan to, such as this one:
It has the advantage of being completely reversible without leaving any trace that it was installed. So there's no need to strip back any of the insulation from the original wiring or install a wire-tap or anything else like that.