Hi Peter. You got me thinking. AFAIK, the Can system looks at the resistance of your light bulb but it has to do that by looking at the current flow and assuming 12v. On the other hand your new LED needs a certain current and voltage and presumably has a built in adapter to give it what it needs from the 10 to 15 volts of a car system.
So I guess you are putting a resistance in parallel with the light fitting? If so you need the highest resistance you can use with out triggering the canbus since heat = V^2/R . If you are only looking at 12v resistors then you are right - lowest wattage. If you are looking at general ballast resistors then highest resistance.
Likely this is Granny and eggs, and that is assuming I am right. Whch often as not isnt the case.
I think you are right. Yes, the ballast resistors are in parallel, so the "brain" sees resistance and so current flow. That works for the side light.
What I don't understand is why I had to put a 3w ballast across the main beam. Without it Main beam would work, dip didn't.
I can only assume that without some load on main beam the dip beam switching circuit wouldn't turn on. I'm pleased there is no ballast needed for dip beam as it is on all the time, the mains only occasionally, and for flashing.
But like you I'm guessing, to be honest with electronics I'm out of my depth.
