ETC "Check Engine Light"

well this morning i went to go pump gas in my truck and my check engine was on the whole time, i smash the gas it goes off, i need to know first how to check my trouble codes and second what ALL the codes mean.. any help please and the sooner the better seeing i go for smog tomorrow

can some one tell me if this site is right? and where the "jumper" is so i can test my codes?

Did the light come on after you got gas? If so check your gas cap. I'll get that other diagram up today.

well its been coming on intermitently and i dont have a gas cap lol im getting one tonight. and also after i got gas my gas gauge went down? wtf lol seems im getting deeper into issues quick with this project which i knew i would lol, anyway can anyone tell me where that jumper will be? and if those codes on that site are correct?

The Bseries computer is basically a fuel management system and u will find it difficult to pull "codes" from the computer.
The "check engine" lite is usually on as a pollution control device service interval reminder.I believe that the small green female recptical on the pass.side firewall is where the "codes"such as they are can be pulled.BJ

so i ground the female and then switch the ignition on and read the codes? i assumed something on my emissions is clogged, and i know i need a new o2 sensor...

That is my understanding.As I said it usually is a pollution control issue causing the lite to come on so a bad 02 sensor will do it.Of course not having a gas cap will do it as well.Lol.BJ

lol i know the idiots who owned this truck are clueless is all i have to say, well we shall see tonight/tomorrow when i take it to the smog guy