I suspect that it is an OBD1 diagnostic port. If your car is a 95 or earlier that is the type of port it would have. Some vehicle information would be very helpful.
Andy

This plug is located directly under the steering column in a huge cluster of wires; some leading to the ignition switch. I initially thought it was part of my crank no start issues I’ve had. I thought best case was the sensor in the ignition lock cylinder disabling the fuel. last night I went through all fuse boxes,(for a second time) and verified all plugs we’re tightly secured, tried a couple of the reset system procedures and to my delight it fired right up and has started for last 5 times. I’m very wary that I “fixed “ the problem and it will happen again. I do know I must learn how to use multimeter as a lot of the tests require it. I also had unplugged the center plug on pcm under the radio and re-plugged it in. So i’m Not sure what the fix was