Well I'm in the process of swapping all of the bulbs in my car with LED bulbs. So far, I'm having issues and figured I'd share (hopefully someone can help).

Swapped out with T10 LED bulbs, no issues:
Dome Lights
Parking Lights
Rear Parking Lights
Backup Lights (required resistors)

3157 LED Switchback bulbs worked fine in the front turn signals but won't light up in amber when the headlights are on... I tried Load Resistors and still didn't work

3157 LED tail light bulbs won't even light up
T10 LED bulb won't light up in License Plate light

Does anyone have any suggestions on how to fix this??

 

I have HID lights in both sets of fog lights and headlights. Could this be part of the issue?

 

Are they installed correctly?
LEDs are polarity sensitive.
www.coms to the bulbs so I can see what you are using...