hey
with the big tail light, there are two lots of leds (some in the middle, and some around the outside, which you should be able to see in the pic).....its only about 6-8 on the outside that dont work............(there are quite a few of em)
it is actual wiring on the led tail light itself, and not from the car........it would be a matter of getting to the circuit board and making sure all the wires are ok (thats what ive been told)......
and they do there own thing, sometimes they will stay on for ages, othertimes they will stay on for a couple of seconds then go on.....led lights with attiutide i tell ya!!! lol