Hi, Goodmorning,
There are several fluids it could be:
Coolant- Which can be many colors but primarily green, and Toyota recommends their orange coolant. Has a sweet smell to it. Check your coolant reservoir for the color of your fluid if you have it filled.
-If it is coolant your water pump gasket could be failing and and leaking on to the belt, however the best course of action is to look at the coolant pipes and hoses for leaks first or check under the water pump for leaks. It is located at the front of the engine, positioned up and to the right of the crank shaft/harmonic balancer pulley and in between the Alternator and A/C Compressor.
Power steering fluid- a darker fluid with a sharp smell to it.
Windshield washer fluid: This can also be many different colors, Primarily blue and and orange, can also be green, purple, and sometimes red.
really just what ever dye the company decides to put in.. check your windshield washer fluid reservoir for the color if it has fluid.
Even could just be water if you are driving through rain or snow and no longer have the splash protection guards under the car and wheel wheels.
possibly but least likely:
Brake fluid: its a clear type oily fluid. if you are finding this on your belt odds are your brake lines are going bad and its spraying when you press the brakes. the brake fluid reservoir is located at the firewall in front of the drivers side.
Transmission fluid/gear oil: Automatic transmissions use a red sweet smelling fluid and the manuals tend to use a thicker clear gear oil. This is less likely to be a culprit because you will notice these fluids under the transmission.
All fluids a described as if they are new and still good, it is possible for the fluid to be older and dirty/rusty.
