[B. W.]

If it has the stock ECM / PCM you can wire in an OBD 2 port. There is a web site (can't remember name) that has the pinouts for the stock computer & for the GM "411" (for switching to the "411" computer, you have more tuning options) Here's what I have:

Data Link Connector pinouts:
Pin 1 - not used
Pin 2 - purple, serial data signal, class B (pin 11, connector 4 on PCM)
Pin 3 - not used
Pin 4 - black, ground
Pin 5 - black/white, VCM ground (pin 17 & pin 18, Connector 3)
Pin 6 - not used
Pin 7 - not used
Pin 8 - black/white, keyless entry (don't know, believe it goes to BCM - Body Control Module) if no keless entry, ignore
Pin 9 - Tan, SIR serial data (same as above)
Pin 10 - not used
Pin 11 - not used
Pin 12 - not used
Pin 13 - Orange, diagnostic signal for TCM (goes to Transfer Case Module, don't know pinout, if 2wd ignore)
Pin 14 - Dark Green, diagnostic, entertainment & comfort (ignore)
Pin 15 - not used
Pin 16 - orange, fused battery