easiest way to see if its just a simple wiring problem is as follows:
1.raise rear wheels
2.find the speedo sensor
3. run 2 new wires from speedo sensor to the connector on the cluster in the y/l y/b pins. put the car in direct drive (4th gear) and observe speedo.
if it works then its a wiring problem. now elminate one of the wires if its still working then its the wire that you havent eliminated yet.
or if you have a multimeter you can check for continuity between the speedo to the cluster that would tell you if you have power going from the speedo to your cluster and would tell you the hud is at fault.
trace the y/b (yellow black) and y/l (which i beleive was yellow green)
this is how to check your speedo make sure it's ok as well
