Hi all. I have searched and looked and am
not trying to re invent the wheel. I have an 09 R56 with 110k on the clock, just did the head, chain , turbo , cat , and lots of other things. I started it and did al that was needed to finish, it ran great, purred. However the next day it would not start. It’s not mechanical, timing dead on etc, bench tested starter, battery is good, key is recognized ( not comfort key)
it clicks and try’s to start for half a second. Then nothing other than the fuel pump running, I’m at my wits end. I don’t have bmw software to dig further into the modules (I usually only do audi, vw) Does this sound like a CAS issue? Any input or experiences with this is greatly appreciated.

Its a R56 S ? If it is then it might be the HPFP... or check de fuse in the engine bay...

I’m up near Sparta. Any who I called rpm and and after a little convo with tech it seems the cas module has bought the farm. 499.00 to get it fixed. for now I just cut the white exciter wire and touch it to 12v + and it starts so I can at least finish putting it back together. The other option is to run a fused 12v + to a momentary switch on the dash and just bypass the cas. And then watch and laugh when some one wants to borrow the mini and can’t start it. :-)

What happened was I started the car after putting it all back together. It was fine, the next day trying to start it. Nothing. No crank, no spin, nothing, but everything else worked and the car recognized the key. I thought I locked the motor up. I spun it by hand, and rechecked the timing , all good. however I could hear the solenoid kick and engage for a split second when I pressed the start button and that was it, sometimes it wouldn’t try to engage either. Looking at RPM’s website , it did everything to a “T” that they describe as a bad cas (ews?) module which is what sends the voltage to the starter to engage the solenoid. that wire is white and followed the large red wire from the starter to the pass side firewall,strut mount area. I cut it on the starter harness side on the connector, pressed the start button, put 12v + to the white wire (going to the starter, not the cas as that may cause some unwanted letting of the magical smoke out of things) and it started just fine. But again this was after testing all other options (Load test battery, bench test starter, checking voltages with multi meter, clean and tighten all grounds, make sure key was recognized ), so as to not throw parts and wasted money at it.

Good luck, please let us know how you make out, so that people can see what resolves the problems and it may help someone else in the future.