96 Z3 1.9 Roadster No Crank No Start

[NBAllen]

Hello to the Z3 neighborhood:

I have an early production 1996 Z3 Roadster 1.9 with a manual transmission.
My issue is no crank/no start. When this occurs the door locks quit functioning as well as the windows.
This has now happened to me twice. Pulled out of the garage one afternoon and rhe car sat for a few hours. Went to start the car and nothing. No crank but dash lights, headlights, accessories all function as designed. Just no crank non-start.
i got out and went to lock the doors to secure the vehicle and I turned the key in the drivers door to lock it (I do not have a remote key fob) and they would’nt lock. Normally i could turn the key and both doors would lock including the trunk.
I left and came back a few hours later and the doors unlocked and the car started. Restarted the car numerous times to try and recreate the issue but no luck.
Drove the car severals days in a row without issues. The second incident was similar but id driven the car to the store. Spent about an hour and half in the store. Came out, nothing. No crank no start windows wont roll down and the lock function is inop again. Just out of curiosity I installed a new battery. Same thing. Left the car over night, came back next morning it started with out issue and windows and locks started working as well.
Any suggestions?

 

[Duncodin]

Security immobilizer playing up?

 

[Althulas]

Hi and welcome from me, possibly could be electrical as well. Unfortunately I’m unable to provide a definitive answer but There’s a few threads on here and .net that possibly could be helpful. Have a search, here’s one electrical related one to start you off….

No crank No start

Hello all, I have a 1996 bmw z3 automatic which will not start in warm weather. It will not even crank. When the weather dips below freezing, the car will generally start. when I put the key in and try to start I hear a click. The overhead light will not come on, and the windows will not work...

zroadster.org

and another about using INPA that could give some insight into the EWS immobiliser
https://www.zroadster.net/forum/viewtopic.php?f=18&t=35789&p=332642#p332641

 

[NBAllen]

Thank you both for such quick replies.

I’ve scoured this site and many others. The start issue isn’t always accompanied by the windows and door locks being inop.
Their issues have been a no start that did temporarily fix itself. They just won’t start.

Any feedback about all these concerns happening at the same time and then they miraculously fixing them selves?

 

[Althulas]

I would start by checking the battery is secure and follow the checks as suggested in that thread to make sure connections are secure and not corroded. The ring for the connection with your car key is behind the steering wheel cowl. It sounds like a possible short somewhere being so it’s intermittent. Only by taking seats and panels out for access are you going to be able to physically check. Or make an enquiry with a electrical car technician who has the experience.