I decided not to go with the AFR gauge idea.
I just redid the steering wheel buttons which turned out to be a little bit of a project. I had two buttons on the wheel before and I found the need for more buttons so I went online and found some real nice buttons that have halo-style lights and are available both momentary and latching which I needed.
I machined the four holes in the steering wheel itsself and also the metal horn retaining ring and actual plastic horn button for clearance with the switches since they need to be close together. With the larger buttons I picked, I have pretty much no room for error as far as their positions on the steering wheel because they will hit one thing or another thing if they're not right where they need to be which is why I went through the trouble to do it all on a milling machine.
Once that stuff was done I wired everything. The original airbag clockspring gives you two wire harnesses and a total of six contacts between the two so that was just enough for me to have four discrete switch circuits, a common ground (which I could have made a local ground but I wanted to have a more reliable ground), and the lead from the dimming circuit for the button lighting so that they would dim along with the rest of the interior instrument lighting.
Wiring was fairly straightforward although I ran into a big problem. I soldered all the wires and stuff up to the original airbag and button harnesses and then when I went to test it, it would completely short out. I couldn't individually test the switches at that point because they were all wired up sharing the same ground so I had to undo all the soldering and stuff just to find out afterwards that both ends of the airbag connectors are actually designed to short themselves out while disconnected - they un-short once they are plugged in. That was why it was all shorting so I did all that rework for nothing gahhh!
The end product looks super clean - I'm happy with it. Also I am able to eliminate that 'perf shift' indicator light underneath the boost gauge because I can see whether it's on or off by looking at the button if it's pushed in or not and I can easily feel or see that day or night thanks to the halo lights on the buttons. I wired it so those lights are always on with the interior lights rather than having the light come on when the button is 'on'.
It seems like everything I do to this car makes it more like a spaceship.
