2005 XC90 with about 65K miles
twice in the past three weeks the same set of problems has cropped up while driving: tachometer, transmission gear indicator, A/C all stop working simultaneously ... in addition, transmission slips terribly from a standing start

the problems persisted for several minutes and then disappeared on the first occasion, second time had to shut down the car and restart, then they disappeared

dealer can't seem to diagnose the problem so they "rebooted all the software" I am concerned that they haven't gotten to the root cause
any suggestions?

 

Maybe a ground strap is loose somewhere? Or maybe the ECM is having issues? I would check the ground strap first especially if any work has been done on the car prior to the problem.

 

thanks for the suggestions have left a message for the dealer's service dept to see if those were among the possible causes that they considered