I modified my dash and the one thing I messed up was my check engine light and now something has went goofy with the engine and I need to see my codes . I know there are wires somewhere you can stick a light between or just count the pulses with a meter and still get the codes but now I can't find the page showing how to do it. Anybody know a page showing how or just want to explain it?

While on the subject anybody have a pinout/wiring diagram for a van dash so I can fix my rigged check engine LED?