E39 electronic erratic problem

Hi all,
I have a 98 540 (E39) and started to have strange behavior from the on board electronics when I start the vehicle. 3 times out of 4 it starts fine, but
when it doesn't, it seems the initiation of electronic routine would not work. The steering wheel does not go down, the radio won't work, horn is down, inside light stays up, DSC+ABS sometimes does not work, I even had the airbag light come up sometimes but rarely.
After few minutes (anything from 2 to 10 min) of driving some systems come back to life but not all. The car would start OK thereafter (after a little resting time but usually not right after). My mechanic told me it could be the battery so I changed it. Still the same problem. He is asking for the car for few days to pinpoint the problem saying its hard to locate elctronic/electric problems. I'm afraid to get a sour bill!
Has anyone lived a similar problem?
Robert
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Replace the ignition switch.
Brett Anderson KMS - Koala Motorsport www.bmwdiffs.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.