If the display function does not work, replace the meter unit.

Check 3-6: Neutral Indicator Light (LED) Inspection
Meter Unit Circuit (ZX1000J Model)Starter Clutch Inspection
Remove:
Torque Limiter Cover (see Torque limiter Removal)
Turn the torque limiter [A] by hand. The torque limiter
should turn forward freely [B], but should not turn backward.
If the starter clutch does not operate as it should or if it
makes noise, go to the next step.
Disassem ...
Vehicle-down Sensor Input Voltage Inspection
NOTE
Be sure the battery is fully charged.
Turn the ignition switch to OFF.
Disconnect the vehicle-down sensor connector and connect
the measuring adapter [A] between these connectors
as shown in the figure.
Main Harness [B]
Vehicle-down Sensor [C]
Special Tool - Measuring Adapte ...
Gear Position Switch Installation
Securely place the springs [A] and pins [B] into the holes
[C] of the shift drum.
Apply grease to the new O-ring [D].
Install the gear position switch [E].
Apply a non-permanent locking agent to the threads of
the gear position switch screws [F].
Tighten:
Torque - Gear Position Swit ...