Is your 82-95 Chevy/GMC  have a check engine light on? Is the dealership telling you that they will charge you $80 to tell you what your truck is silently telling you? Well fear no more! OBD-1 is (on-board-diagnostic) yes, onboard.  I will explain to you how to figure out what your truck is telling you. it isnt hard and only will require a piece of paper. a paper clip, and a pen. yes, its that simple.  Ready? lets begin.

On every vehicle you have a diagnostic port underneight the steering wheel collum. if you get down you will see little pins sticking out of them, it is almost as though something is ment to slide on. well there is such a tool but we wont bother with that.  Now. Make sure your truck is off with key out of ignition.  Take the paper clip and open it up. make the paper clip into the shape of a U with a quarter inch separating the ends apart.  While looking at the Diagnostic port, you will see some openings all the way across the top and bottom.  the TOP row all the way to the RIGHT. so the TOP RIGHT TWO OPENINGS (sorry for the large print, I just want to make sure some people insert the paper clip into the corect holes) Insert one side of the paper clip into the hole to the top and to the farthest right. The other paper clip sould be inserted to the hole directly to the left. so it would be the second to the right.  Now, Sit in your trucks seat and get your pen and paper. be ready to write some numbers.

only do this next step when you are ready. you might want to get a friend to read the code while you write them down.  the code will come out like morse code in a way.  

After turning the key the check engine light will Blink "12"  When I tell you a number, I mean it will blink as so.  for 12 (which is the begining code, dont worry, it means nothing, it is just letting you know that the computer is working and the trouble codes are being brought up) it will blink as so

" 1 " " 1-1" <---12. see it?  Now if you were to have a trouble code of....

" 1-1-1-"____"1-1-1-1-1"____________   that would be a trouble code of 35.  Get it?  then it will pause for a bit longer and throw out  "1-1-1-"____"1-1-1-1-1"_____________. easy eh!

Here is a list to a webpage that lists GM Trouble Codes.

goto a search engine and search for "GM trouble code list" you will find a list of trouble codes to compare to your findings.

you get the codes, Un hook the battery for about a minute, and then rehook it up to get the computer back online. If any new codes apear, the computer will remember it.