Whoops, wrong photo. I meant to attach this one:I think you might want to re-read his post once more.
Just to add to clinebarger's post...
"The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU. The skid control ECU converts these wheel speed signals into a 4-pulse signal and outputs it to the ECM via the combination meter. The ECM determines the vehicle speed based on the frequency of these pulse signals."