I have a 1985 Cadillac Seville Elegante 4.1 litre V8 and the Service soon light is on. NOT the Service Now light (which is the check engine light.) I want to know how to shut it off... i know that I can read and erase codes by the on board thermostat in my car, but that doesn't work.... Please help, It's driving me NUTS! I was thinking the light is on for like regular maintenance stuff, but i do all that, why wont it shut off?! Is there a button or switch somewhere? Please help and thanks for your time.