I agree with Leeann on this... I use a USB cable and software on my '95, simply because it's an OBD1.5 vehicle,my '87 G body and Suburban would get the code reader if I wasn't too cheap to buy one when I can use a 2 cent paperclip, lol. I use an OBDII reader for the '99, but I need to get the usb cable and scanner software or buy a real scanner. Man I miss working for GM and having access to the Tech2 and GM database.(not to mention the parts discount)