I have a 2000 BMW 323i with 140,000 miles on it, which has intermittent starting problems. This usually occurs after trying to restart the car within 5 to 10 minutes after turning it off. After several attempts and 10 to 15 minutes, the car does always restart. When the problem occurs, the engine does not turn over at all, but the electrical system seems to work. The dealer has been unable to duplicate the problem.
By “the engine does not turn over at all” mean that there is no cranking? The starter motor is not working? Is there a click each time you turn the key to the start position or just no noise at all?
No noise at all.
Well that could be strictly an issue with the starter motor. It maybe getting hot enough that a primary connection is lost. Unfortunately there are a couple of other things that could also cause this so you are going to need a mechanic to perform some tests.
You need to make arraignments with a good mechanic so that when you bring it in, they can begin to troubleshoot the system while the problem exists. Wait too long and they won’t be able duplicate the problem.
The first step is to see if voltage is getting to the small terminal of the starter. If it is and the starter doesn’t turn, then that needs to be replaced. If no voltage at the starter, then it could be the park/neutral start switch. BTW, when it doesn’t start for you, hold the key in the start position and shake the stick. If it still doesn’t work, put it in neutral and try again.
If the mechanic determines there is no voltage at the safety switch, then it could be the ignition switch or the main fuse. I would not expect the latter as the other things are working.
I don’t have access to a beamer wiring diagram so there could be other components involved, maybe an underhood circuit breaker.