I have not seen any posts with these problems. 04 Deville with 72000. When I start in morning, these things happen. Service Airbag light comes on, tach does not work(shows 0), speedometer not working(shows 0), turn signals not working. After a short time of running, all of the above functions work but the Check Engine light comes on with a P0449 code.(Evap vent solinoid). Any help would be greatly appreciated.