No OBD II output

[millssy]

I have a 2003 Envoy that I can not get an OBD II reading from. I have taken it to 3 different "Name Brand" parts stores and also borrowed a coworkers code reader and had no luck. I even took off the plugin to check for loose wires, I know the reader worked as I recieved a couple of codes for my mercury. Is there an inline fuse that would cause no power to run the code reader?

The service engine light is on with the Envoy doing the following:
Light is constanly on, then will flash during acceleration
Rough running/ ideling
Will not start all the time (often will act as if I have disconnected the battery when the key is turned to the start position)
Gas comsuption is up

I have read several other posts that lead me to think that the starter solenoid is going out. I have checked all connections and made sure that there was no corrosion and all were tight.

[maxwedge]

Welcome to AF. Check the body feed/liter circuit fuse, that is usually what powers GM obd11 ports.