Computer Won't Read Out Codes

I've had my service engine light come on a few times since I've owned the vehicle (twice when I unplugged sensors in order to intentionally make it code). A reader that I KNOW works comes up with code 0 every time. I AM able to clear the codes however.

Could this just be a bad connection? If so, is there a pin out available?

Are you using an OBDII compliant code reader?

Yes indeedy

Yes indeedy

I would check to see if all the connections at the PCM are tight and clean.

Also check the connection at the communication port to see if one of the connections there haven't pushed out the back of the connector.

Is your PCM in the dash or on the passenger side fender?

Does yor cigarette lighter work ? Some code readers need power from the OBDII connector which is pin 16 ( battery power). Many GM's have pin 16 on the same circuit as the cigarette lighter. If cigarette lighter does not work check the fuse or use a light probe to verify you have 12 volts at pin 16.

No fuses blown anywhere on the vehicle. The PCM is passenger side fender, right above the coolant reservoir.

I'll double check all those connections tonight, and maybe bust out the brake clean + toothbrush. Thanks fellas.

Edit: and yes, the cigarette lighter works