Tachometer "climbs" when key is on.
This is a result of the cylinder selection COMM PORT selection wires not being connected or the plug is not fully seated.
Check that the plug is properly installed, seated, pins straight and COMM PORT wires connected
The gauge may be pegged at max on the high limit stop. CLICK HERE FOR HOW TO FIX
If this does not work please contact NVU cistomer service at 248-850-5482 have the code GTC5011 available