Does a 97 Deville have a air bag sensor under the front seats The service air bag light stays on most of the time but seems to go off after someone has been sitting in the passenger seat?

In late 90's GM passenger cars, the computer that controls the SIRS (Supplemental Inflatable Restraint System) is mounted underneath the passenger seat. If someone sitting in that seat causes the light to go off... you probably just have a loose connector. Always remember to pull the main airbag fuse (normally located in the engine compartment) before touching anything to do with the airbag system. Failure to do so could result in severe injury.