1998 BMW 740 Electrical issues on BMW

I have a 1998 BMW 740il with approximately 82,000 miles. In the last month the car has developed an issue with the interior electrical functions. This problem comes at goes with no apparent reason and the actual issues change.

At the first occurrence the turn signal indicator did not work although the outside turn signals did work. The radio stopped working as did the electric seats. The issues went away the following day.

A few days ago the turn signals did the same thing but the radio worked although it would not change stations.

I spoke with the BMW service tech at the dealer would told me there is some 60 miles of wiring in the car and there was most likely a short somewhere. He did not even want to work on the car.

I do have a good mechanic who has worked on my cars for years and I have ordered a wiring manual for him. Any ideas of where he can start?