So you picked up a brand new car. - a Lexus no less - and found something didn't work, but instead of contacting the dealer you went and bought a replacement part and tried to fix the problem yourself? What am I missing here?
Being a Noob when it comes to this you should have contacted the dealer directly before testing it with anything aftermarket. Dealers can be a pain in the ass and say that w-e you did caused the problem. However that being said the first thing you should have checked for was reversing the bulbs polarity by just turning the bulb to insert on the opposite end. if not the next step would be testing the socket for current with a meter or test light. In the event that you don't have a test you can attempt to check the fuses to see if the fuse may be bad or even missing. (you would be surprised how many times this actually happens with new cars).Just picked up my car yesterday. Drove it later that night and noticed the footwell lights were not working. I replaced the bulbs - nothing. Used the LED replacement bulbs I bought - nothing.
I am a noob when it comes to this. What may be the issue?
Put the OEM bulbs back in. Do the overhead lights work as they are also tied into the door switch? If not go back to Lexus and have them fix it.If I were you i'd replace the OEM bulbs, go back to the dealership and have them diagnose the issue, just never let them know about the LED bulbs. For all we know, the lighting issue can be as simple as a bad fuse for the foot well lights, or something extensive like something to do with the wiring harness.