Back probed the VSS and the input signal at the instrument cluster.
Yellow = Pin 17 (signal) at the instrument cluster
Green = Pin 3 (signal) at the VSS
Red = Pin 2 (ground) at the VSS
That obviously doesn't look right. Pin 2 (red trace) isn't grounded.
Looking at the sensor diagram it should be a 12v square wave.
So where's the ground?
Visual inspect revealed the ground was a bit dirty.
Cleaned the contacts put a thread chaser through the hole and installed a new bolt.
And... No change... Is this the right ground? Mitchell says the ground is behind the dash but the image supplied by Hyundai says different... And there's no continuity between the ground and the VSS pin 2. A broken wire? Maybe. But I had no desire to track down a ground with an uncertain location. A quick visual inspection of the harness between the supposed ground location and the VSS revealed nothing.
At this point I stripped back the wiring a bit, soldered a new ground wire in and bolted it to the engine.
Looks good to me.
Hope this helps someone in the future from throwing away money like the customer did. About a half hour of work and no parts replaced.