Most systems have the washer pump installed in the bottom of the windshield washer fluid reservoir. Some systems use a constantly running pump where as a few systems such as the older General Motors used a pulsed pumps that operates off the wiper motor. On these systems the washers only worked after the wipers swiped a few times. On most domestic cars the washer fluid is activated by holding the washer switch most often located on the turn signal stalk that is often integrated with the windshield wiper switch.
On many vehicles an override circuit is provided in the module that operates the wipers at low speed for a program length of time after the washers have been activated and then the wipers park. They do this because it really doesn’t make much sense run the windshield wipers without the washers or run the washers without the wipers operating. After they run for a length of time the wipers either returned to the park position or operate in an intermittent mode depending on the design of the system.
Washers on Fancy cars
Some vehicles are equipped with a washer fluid indicator light. This is usually a float type system where the light is turned on to notify the driver that the fluid is low in the reservoir. Of course like any system this can malfunction and a false indication can be displayed. I have seen the float get hung up and not notify the driver that no fluid remains in the reservoir when indeed there is.
My point of this is that regardless of having a warning light you should still take the time to check the amount of windshield washer fluid remaining in the reservoir. Even though topping off fluids is included in most quick oil change services it doesn’t always mean that it gets done. Being proactive and making a quick check before a long trip can assure that you have fluid to squirt on the windshield when you need it. Dig into more online auto repair information.