Pulled off the bulkhead to look for the elusive black and gray wire coming out of the speedometer.
Found it coming out of the plug on the speedometer, but it disappears into a wire loom, never to emerge.
I took a wire and soldering a fine pin to it. I inserted this into the back of the speedometer plug where the black and gray wire emerges.
Used this set up to run the calibration, that way I did not have to cut into the wire.
