I just got this 2000 Z28, it had the service engine soon light on, thats an automatic fail, so a buddy of mine showed me how to take out a couple fuses for like 5 minutes and make it turn off...when i took it to smog it ran exceptionally clean but still failed because it, "failed to successfully complete all OBD self tests" and the part the failed was MIL/Check engine light. The people that smogged my car told me to just drive it for a week and bring it back and it'll pass. Other people are telling me that i need to clear the codes from the ECU memory or something like that, i have no clue how to do that...any insight on my situation would be helpful

 

That is a OBD II type PCM, just taking fuses out and pulling the battery cables loose will not completely erase the PCM's memory or any diagnostic codes that are in as hard faults. There are occasions, depending on the code, that taking the negative cable off the battery, letting time pass for the PCM to brain drain can "reset" the system. What you run into though, when they smog it the scan tool they are using is looking for the parameters to run for certain systems, if the fault that set the light keeps them from running, they will never run, and set the light.

You'll need a scan tool that is capable of clearing the PCM's memory. What was the codes that where listed, that may very well explain the reason they didn't clear from the memory?