Service engine code reading?

I have a 2001 Tahoe. Recently the service engine light came on. Is there a trick way of reading the codes without buying a reader? On my 1984 and 85 Corvettes I was able to use a jump wire to connect the first and last terminals on the reader port to get the light to flash the code. If this can be done on the Tahoe how would I do it and where would I find a listing of the codes?

What you're describing was the way to extract the codes on OBD1 (pre 1996 ) it doesn't work that way on OBDII which is what you have. 
Take it AutoZone they'll read your code for free.

golfer is right.  Autozone has a reader.