Hello y'all I'm installing aftermarket lights on the outside of the truck (2017 Ram 2500 Laramie Power Wagon) and want then to come on with the dome light when I unlock the truck. Now does anybody who is really good at wiring know how to do this so they don't come on when I turn the done lights manually. Really appreciate the help!

 

Does your truck have puddle lights under the mirrors? If so, that circuit should function mostly as you are desiring. Of course depending on how much current these aftermarket lights draw will determine if you have to use a relay with the lights or not. Otherwise you'd be stuck building a logic circuit with an Arduino or discrete parts to only trigger the light when the unlock circuit pulses AND the dome lights are on.

-Rod

 

I wouldn't tap into the mirror lights or the bed lights if you have them, they are LEDs. There is not enough current there. Many things go on when you unlock the truck, the rear lights, the head lights, trailer lights circuit also comes on. Tap into any of those to run a relay or two.

 

What is involved in a logic circuit? It does not have the puddle lights as this is why I would like to install courtesy lamps. I did socialize in writing at a different garage but even though I'm young and not good at computer programming. Thank for your help! Is there like a starter kit you can buy for logic circuits?
I thought about that too but the same would apply. Whenever that light is turned on it will light up the outside courtesy lights. Appreciate your help guys!

 

There are starter kits for Arduino that would allow you to write or "borrow" code to do very specific tasks based on inputs. Although depending on the particular Arduino the inputs would need to be level shifted to either 3.3V or 5V, and really an Arduino is overkill for what you are trying to accomplish. You could almost as easily just use a handful of diodes and transistors to provide an AND logic function which would provide virtually no load on the input circuits, then use the output of the AND gate to drive a transistor (versus a relay) to light the courtesy lights. I doubt you would need to spend very long in a Google search to get several simple "AND gate circuit" examples using 2N2222 transistors and 1N4001 diodes. Part of the benefit of using discrete transistors to build the gate versus buying a packages AND gate IC is with the transistors you will not need to worry about level shifting the voltage from the courtesy lights or ignition.

-Rod

 

I got most of that and I really appreciate you taking the time to reply. As this question probably pops up a lot. I figured if I get these courtesy light installed I could then tap in my puddle lights for the mirrors I plan to install. I will do some research and if I have any questions would I be able to ask you? Thanks again!
Austin

 

Certainly.

-Rod

 

So reading into the AND gate I think I have what I need (please tell me if I'm wrong) what I would do is this. Take two inputs (something that comes on when be I unlock the doors so the dome lights and maybe the left turn signal) add transistors and then wire the output to the lights. Am I missing anything? I chose the left turn signal because how often we have the dome light on and the left turn signal on at the same time.

 

Well, as I think about this more, I am thinking you want something more like input 1 to be the dome light circuit and input 2 to be an inverted ignition source so that the new lights will only come on when the dome lights are on AND NOT the ignition. So you can use another transistor to invert the ignition input to the AND circuit.

Depending on how much current the new lights take you may also need a high current driver transistor that is triggered by the AND gate to drive the new lights.

-Rod