2008 GMC Sierra Electrical problem

Recently while using the turn signal to change lanes, my speedometer and tach go crazy and jump around. The odometer will go blank or tell me to service airbags, the transmission down shifts and stays in 3rd gear, clock always has to be reset, the gear indicator on tach face will jump between D and Park causes the truck to jolt and the air bag warning light flashes. I usually pull over, shut off the truck for a few seconds and that seems to work sometimes. I've read blogs and forum from people with, I think, have the same issues and come to the conclusion it could be the TCM or BCM. Is that my problem?