I had a similar problem with a car I was working on in my shop. All the guages would jump around and after extensive searching I found that the airbag module under the passenger seat was getting wet for years from the bad water problem on many grand am/prix. And after a while the car wouldn't even start cause the module was shorting and the car tought someone was stealing it.It can be disconnected and everything should work normal again except you Won't HAVE AIRBAGS!