If the fuel level indicator light (1) does not function properly, check the fuel level gauge and its lead wire/ coupler.
If the fuel level gauge and its lead wire/coupler are functioning properly, replace the combination meter with a new one.

Engine coolant temperature indicator light inspection
Fuel level gauge inspectionWater pump construction
Impeller
Mechanical seal
Oil seal
O-ring
O-ring
8
N·m (0.8 Kgf-m, 6.0 Lbf-ft)
10 N·m
(1.0 Kgf-m, 7.0 Lbf-ft)
Apply grease.
Apply engine coolant.
Apply molybdenum oil
solution.
Do not reuse.
...
Cooling circuit inspection
Do not open the radiator cap when the
engine is hot, as you may be injured by
escaping hot liquid or vapor.
When removing the radiator cap tester, put
a rag on the filler to prevent the engine
coolant from spraying out.
Inspect the cooling ...
Voltage check
If voltage is supplied to the circuit being checked, voltage
check can be used as circuit check.
With all connectors/couplers connected and voltage
applied to the circuit being checked, measure
voltage between each terminal and body ground.
If measurements were taken as shown ...