When I install some packs not all the Vehicles lighting system doesn’t work the lights stay on but they don’t flash, and as well how do you add all vehicles that are in packs to the game to replace all vehicle I would appreciate if someone could help.

most modders add a read me file, that will help you a lot, some people add ELS models without stating they are, try using the search bar and see if you can find anything related to your problem, here is a little help https://www.lcpdfr.com/search/?q= lights stay on&type=forums_topic,  replacing vehicles... you can try to search on youtube on how to do that, having a visual on what is going on is always helpful