SINCE 2004--Professional Auto Diagnostic Factory

Most vehicles that were manufactured prior to 1996 use first generation on board diagnostic (OBD) systems that are collectively referred to as OBD-I. The first 

OBD-I systems showed up in the late 1970s and early 1980s, and every manufacturer developed their own interface technology. That means that while these 

systems are grouped together into the general category of OBD-I, they share very little in common. Every manufacturer had its own, proprietary OBD-I plugs 

and jacks, and many OBD-I scanners were designed to work with vehicles from only a single make or even model.

The good news is that, in many cases, you don't actually need an OBD-I scanner to read codes. The bad news is that every OEM had its own way of accessing 

codes without any diagnostic tools, so the situation is anything but simple.