Here's a small contribution - your car is not OBDII - SL320, S320s and C280 were the early adoptors. Your car has a 16 pin diagnostic connector located near the battery. The built in LED light and pushbutton reads only the DM (diagnostic module), for other systems you need to build the code reader from Radio Shack parts. You actually need 3 different things - LED, banana plugs (3) and a momentary switch, still less than $10.