e39 no strat-confusing one

[robc46]

hey guys, hoping you can help here. I have a 2002 530i (CK17534) just recently, at random times when i go to start the car i will just get a tick tick sound like a dead battery so i hook up a jumper car, go to start and get the same thing, tick tick, big current draw, no start.

i can start the car by shorting out the starter terminals with a screwdriver, then the car will be fine besides a dead battery.

i've changed the ignition switch and all was going well for 3 days but this morning it just happened again.

Im guessing ive got a EWS issue but i want to know how i can find out for sure before i go changing more things.

Thanks heaps