Well, this is an oddity (at least to me). I knew that 1995 was the last model year before OBD-II came and straightened everything out, so my '95 Monte had something referred to as "OBD 1.5". It has a twelve-pin socket (whereas the OBD-II ones have sixteen, I believe?) ... but until recently I haven't taken a real close look at it. But for a few months now the "AIR BAG" warning light stays on consistently, so I had my shop look into it, and they tell me that the car's OBD socket has only two pins in it -- and nothing they had would connect and communicate with the PCM.

Here's a pic of the little oddball:


The only two pins it has are on the far right.

Wikipedia's article on on-board diagnostics mentions that GM had a wide and inconsistent variety of ALDL (Assembly Line Diagnostic Link) sockets in their cars until 1996. Apparently so!

The things I can't figure out are:
• How is this supposed to work with only two pins? Shouldn't it have at least three?
• Didn't this ever present itself as a problem for the car's previous owners, when they brought it in to their shops for maintenance?

Weird. Just weird.

 

I know the 80's GMs (like my 84 Camaro), you could jumper a couple pins and force the car to flash the CEL in patterns to expose the code.

Pre-ODBII did not have power at the connector like ODBII does (it sucked, you had to plug the scan tool to the connector and a cig lighter and if the lighter was dead, some gave you alligator clips to go to the car's battery). ODBII is super nice giving power, ground and data.
I am guessing your connector has a data pin and a ground or it's two pins required for data.

 

I am not sure how they should be. I had a 95 MCZ34 and I had one that was 12 pin and only A an M were present. One of my friends had a 95 that had 3 pins. With his I was able to Jump A and B pins to get the dash to flash the codes. With mine I was told by Chevy when I took it in for service. My car was an Older 95 system and my friends was built after mine and had the updated port.

I am going to guess that your car is also with an older OBD port and only offers Ground at A and the Serial Port at M.

 

that sounds logical as the Brickyard MC was introduced in 94 to coincide with the 1st Brickyard 400 for Nascar.
If you have the local GM dealer check your Vin# they would be able to tell you when the car was made.

 

Hmmm, you don't suppose a Chevy dealership would be the only place that could read the airbag (and any other) trouble codes on this car; sure, it's a viable option (there's one just a few miles up the road), but I guess if no other place could, they would.