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

Check 3-6: Neutral Indicator Light (LED) Inspection
Meter Unit Circuit (ZX1000J Model)Crankshaft Sensor Peak Voltage Inspection
NOTE
Be sure the battery is fully charged.
Using the peak voltage adapter [A] is more reliable way
to determine the condition of the crankshaft sensor than
crankshaft sensor internal resistance measurements.
Disconnect the crankshaft sensor lead connector (see
Crankshaft Sensor ...
Air Cleaner Oil Draining
A drain hose is connected to the bottom of the air cleaner
to drain water or oil accumulated in the cleaner part.
Visually check the drain hose [A] if the water or oil accumulates.
If any water or oil accumulates in the hose, remove the
plug [B] from the drain hose and drain it.
...
Tire Air Pressure Inspection
Remove the air valve cap.
Measure the tire air pressure with an air pressure gauge
[A] when the tires are cold (that is, when the motorcycle
has not been ridden more than a mile during the past 3
hours).
Install the air valve cap.
Adjust the tire air pressure according to the specifi ...