the cluster in the the car, is standalone,
its just a display and has self test you can do.
Check both cluster fuses in the fuse box yet?
one is power other is memory.
if that test passes, and you
THEN PCM, did you scan it yet? (any modern $10 scan tool works here) can-bus rated, scan tools are Ubiquious now.
not scanning the car, and missing can-bus errors is bad idea.
or missing PCM can't talk to the display(cluster) misses the boat.
or VSS errors, or any TCM errors, or other errors, DO SAY THEM.
the PCM sees RPM or the engine can't run , with dead cam or crank sensors. so right off the bat I know PCM is sending RPM .(tacho)
the speed can be checked with any scan tool made (rpm /speed)
plug in scan tool and drive, and have helper read the PID called, SPEED . (vss speed) cheap tools can do live data stream.
on ANY PID. (pids are live parameters by number)
do not guess. here, scan it first.
or go broke.