If the surface is corroded or if the blades are damaged, replace the impeller

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyAntenna Resistance Inspection
Turn the ignition switch to OFF.
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Disconnect the antenna lead connector [A].
Measure the antenna resistance.
Antenna Resistance
Connections: BK lead ←→ BK/W lead
Standard: Ab ...
Clutch Plate, Wear, Damage Inspection
Visually inspect the friction and steel plates for signs of
seizure, overheating (discoloration), or uneven wear.
Measure the thickness of each friction plate [A] at several
points.
If any plates show signs of damage, or if they have worn
past the service limit, replace them with new on ...
Exhaust Butterfly Valve Actuator Sensor Resistance Inspection
Turn the ignition switch to OFF.
Disconnect the exhaust butterfly valve actuator sensor
connector (3 pins connector) [A] (see Exhaust Butterfly
Valve Actuator Sensor Input Voltage Inspection).
Connect a digital meter [B] to the exhaust butterfly valve
actuator sensor connector.
Measur ...