footwell lighting

I'm wanting to wiring in footwell lights but unsure how to make all the power sources give off the same amps. I want the lights to fade on/off with the dome light when I open the door and unlock the car. And also want them to come on when the headlights are on at night. So I'll have two triggers to turn on the lights, dome light wire and headlight wire. I know which wire to connect the lights to so that the lights fade on and off with the dome light. I plan on connecting it directly to the lights so that the fade works correctly. But my headlights come on for a 30 sec timer when I unlock the car as well. So I don't want the headlight wire trigger to affect the fading. So I want to have the headlight wire triggered by a relay and the 12V source for the wire be an Ignition power so that the headlight wire trigger only works when I have the key turned on. Main thing I'm worried about is that the lights will be too dim with dome light and too brght with the headlights or vise-versa. I want them to be consistent. Is there a way to measure say the amp output going to the lights and then use resistors to get the two sources to have an even output? My plan is to have one relay with 12V constant going into the second relay triggered by the ignition, then the second relay triggered by the headlights going to the footwell lights with the dome light wire also tied in. With various diodes plugged in to prevent all the back feeds of course. Does this sounds correct to you? And where would I place the resistors so that the final wire going to the lights is always the same amp regardless of which trigger is powering it ? Thanks!! (Sorry for the book I just wrote)Never stop learning

2011 Chevy Camaro btwNever stop learning

If using LEDS, current is not a huge issue. Also, if you want them them to DIM with the dome, then you need to connect them to the same Circuit, and that's a Body Control Modulator. LEDs tend to actually stay ON all the time with new cars and their auto dim feature. Mine are always on, VERY dim though, when they fade out. Incandescent bulbs do not light up with this lower current because they require more to light. IF you then want them to come on with the headlights? Then you need to DIODE ISOLATE the power from the BCM, so you don't blow it out when you turn the headlamps on. You can use a relay, but then you have BULK, when the DIODE will work just fine. You need your wiring information to add them, that's all..

If using LEDs and you want them to dim in proportion to other bulbs, you need to use PWM. Being a new vehicle, PWM would almost certainly be used in your dome dimmer (unlike pre-1990s vehicles that used analog transistor circuits, and rheostats/variable-resistors for manual dimming). I'm not familiar enough with your wiring to say how to interconnect the different triggers (relays, diodes, etc).

I have replaced all the lights in my Interior with LEDs, and they DIM just like the incandescent bulbs did, except they don't fully go off. I didn't use a PWM, and you do not necessarily need one. You can tap right into your DOME light wires, or other place where you have lights that DIM now, and run them down to the floor. It's a little more work. Usually, the harness is under one of the "A" Pillar covers. LEDs use mush less current. The only ones that do not go all the way off are the front dome lights, the rear courtesy ones dim to all the way off. In my Jetta? The front 1 and rear 2 stay on all the time. There is always voltage going through those lights with a PWM, it's just that there isn't enough to illuminate an incandescent bulb, but there is enough to have LEDs lit up dimly...

powerslave - are you saying you have incandescents and LEDs off the same dimmer, and there is no appreciable difference (ie, non-linearity) in brightness between them as they dim, AND you are NOT using a PWM dimmer? I dare suggest that if they are reasonably proportional, you do indeed have a PWM dimmer. I also doubt that a Jetta does not use a PWM dimmer. Furthermore, that the LEDs do not fully extinguish does suggest OEM PWM as these rarely turn fully off especially if fitted OEM with incandescents (unlike resistive types that will extinguish LEDs paralleled with incandescents). With resistive and analog dimmers, LEDs will tend to remain fairly bright compared to parallel dimming incandescents, but then relatively suddenly LEDs will full extinguish. (IE - far from "linear" behavior.)

In my Charger, I originally just had 194 5SMD 6000k Bright LEDs in back, and the incandescent 578s up front. I did not have the Festoon LED 16SMD panels yet. Yes, both the fronts and rears dimmed out evenly, and the fronts were completely off. I later replaced the 578s, with 578 Festoon LED panels up front later. Those are the ones that stay on DIMLY now. The ones in back, do not, and they all DIM at the same time. All I was indicating, was using LEDS, they use less current, and will stay illuminated dimly. Incandescents use more current, and once the lights dim off, there isn't enough going through those to light them but there is current there,enough to light LEDs.   I did not say I mixed bulbs, at all, but I did in the Charger, not the Jetta. For the fun of it, this week, I will put a 578 OEM back into the front of my 2013 Jetta, and leave the 578 LEDs in back, and see what it does, then put OEM in back and LED in front, see what happens...

So is/are yours linear, or PWM? I was clarifying 2 things- Firstly your "I didn't use a PWM which some might take to mean you are not using a PWM as opposed to you not adding one etc. Secondly that if you want linear or proportional LED dimming - whether proportional to parallel incandescents or proportional to pot/wiper sweep, then PWM is almost certainly required (though current limiting can be use if dedicated LEDs, but...). Current is essentially irrelevant. Linear pot/rheostat dimmers effectively decrease voltage (linearly) which works fine for incandescents whereas LEDs require (linear) current reduction. PWM essentially achieves both.    I'm assuming your dimmer is PWM based on the behavior you describe.

I think I explained my plan wrong becuase I dont think i got my question across correctly.

I plan on tapping into my domelight directy and running it to my footwell lights. (right now my LED domelight dims perfectly) And I'm guessing my domelight wire amp output is going to be lower (like maybe 3-5 amps) vs the headlight power wire I also plan on tapping into and also directly running it to my footwell lights. (I'm guessing it will be 10amps) I may be completely off on my guesses, this is just for an example.

So one wire = 5 amps going to lights

Other wire = 10 amps going to lights.

How do I test a wire for its AMP output? how do I make sure that both wires will put out the amp 5 amp output.

I'm guessing when my footwell lights get 10 amps it will be brighter then when they get 5 amps. This is my main concern.

Hopefully that makes more sense

Never stop learning

You don't "push" Amps into a load. Your footwell lights will take whatever current they require irrespective if connected to a 5A or 10A circuit or the battery directly. Your only issues are: - ensuring the lights are 12V - ensuing they dim proportionately (hence PWM if using LEDs) - how to common the lights to be dimmed to the same dimmer or trigger (and if the dimmer handles the total load).