Faulty Instrument Cluster? Trans Failsafe Mode

[Caravelle]

My 2002 4.4i X5 has for a few months been displaying warnings for DSC and Tyre pressure every now and then. Also the factory navigation unit has been freezing up and rebooting frequently. The other day the transmission went into fail safe mode.

I took the car to the local BMW workshop. After they plugged in the diagnosis tool it turned out that the engine water temp reading was above boiling point while the radiator outlet temp was still normal. Either way the workshop said they upgraded the software in the cluster since they couldnt diagnose properly. That didn't help anything and the transmission was still in the failsafe mode.

The workshop just said that they wanted to replace the instument cluster with a brand new one, and that that might help. I didn't have any confidence for this workshop since they seemed to have no clue how to even diagnose the problem. When I drove of with the car I notuced that all the spedometer and rev meter were dead. The temp meter would go up and down like crazy. The navigation unit also rebooted itself and went into some mode with simplified graphics.

Now the car is at another workshop that is supposed to be better. The gearbox was working perfectly fine before anything of this happend, and still does when the engine is started cold.

What do you guys think the problem can be? Is it the cluster, or something else?