Speedo Concerns

1988 Cali cars with mass air did have a check engine light. However, if you stick a bulb in the socket in an 87-88 car, the light will come on when you start the engine, but it's not connected to the self test input to display the light.

If you wish to test this, unplug your EGR. Light should come on.

No 140mph speedo in 1988, I'm guessing someone swapped in an 1989 cluster which had the check engine bulb installed. It should display upon startup. You need to run a wire to make it functional.