hey guys i am working on a impala model, and the taillights/brake lights don't work in game and i have no idea why. i have checked the hierarchy and everything seems fine. any advice?

You need to use lights(vehglass) material on the vehicle glass that covers the tail light, and also you need to make sure the vehglass material is lower in the material section then the materials you use for the tail lights (usually lightsemissive). If it's not, you need to go to faces mode, select the covering glass parts, detach them, create a new lights(vehglass) material (you can just copy it), apply it to the glass covers, then attach them back to the taillight.

Also make sure that the tail lights are higher in the hierarchy then any other glass materials that covers them.