So, i finally got around to trying to make cars for gta 5 again. And igot my lights to work in game when i turn on the sirens, but when they are off, the lights stay on like a steady burn, and i cant turn it off.

The pivot and the mesh are at the same place.. in other words, the axes on the siren can't be centered on the actual object. 

The game makes the siren emissive two times larger and casts it two times further away from the dummy .. Check the attachment at the end of the first post in F5544's thread here 

if you don't understand, import a vanilla police car into zmodeler and take a look at how its sirens are set up...