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

Check 3-6: Neutral Indicator Light (LED) Inspection
Meter Unit Circuit (ZX1000J Model)Periodic Maintenance Chart
The scheduled maintenance must be done in accordance with this chart to keep
the motorcycle in
good running condition. The initial maintenance is vitally important and must
not be neglected.
Periodic Inspection
#: Service more frequently when operating in severe conditions; dusty, ...
Bolts, Nuts and Fasteners Tightness Inspection
Check the tightness of the bolts and nuts listed here. Also,
check to see that each cotter pin is in place and in good
condition.
NOTE
For the engine fasteners, check the tightness of them
when the engine is cold (at room temperature).
If there are loose fasteners, retighten them to ...
Sidestand Removal
Raise the rear wheel off the ground with the stand [A].
Remove:
Sidestand Switch Bolt [A]
Sidestand Switch [B]
Remove:
Spring [A]
Sidestand Nut [B]
Sidestand Bolt [C]
Sidestand [D]
...