If the pump under the hood buzzes and makes noise when you press the washer switch then the sprayers at the windshield are plugged, replace sprayers. More likely you will find the pump makes no noise and is bad. Could be out of fluid.
MOTOR FOR WIPERS
If your windshield wipers are not working, you should check your owners manual. It could be a fuse or another easy fix.
If the windshield wipers work when pushing the lever down but not when they are turned on all the time, the problem could be in the wiper motor relay switch. There are two different relay switches for the windshield wipers, so that if the one fails a person can still clear the windshield manually.
Dryness will cause the wipers to vibrate or jitter against the glass. If there is not enough moisture on the windshield (for example, a light sprinkle of rain) the wipers may move with a jerky motion. Also, the wipers could be very old, and the wiping rubber/vinyl could have lost some of its softness and flexibility. If you mean vibration when they are not active, the wind against the windshield could cause them to flutter if they are not properly seated. A clean windshield and new wiper blades will usually cure the vibration.
They could see through the window better...
If the windshield wipers are not working in a 1998 Ford F150, the cause could be a blown fuse. There could also be a problem with the vacuum hoses connected to the wiper motor or the wiper motor itself.
I use to put cardboard on the glass under the wipers, leaving the wipers laying on the cardboard to hold it in place. Unless it is raining, the cardboard does not get soggy, and does not freeze to the windshield and the wipers do not freeze to the cardboard. I lived in PA for 38 years so I have dealt with ice and snow. Then I wised up and moved here to Arizona. 70 degrees today..................sorry to tell you! You could also put a sheet of plastic between the wipers and windshield. You have to start with a dry windshield and wipers so the plastic or cardboard does not freeze to either.
The windshield wiper was invented by Mary Anderson in 1903. Clever and efficient. The windshield wiper is use to remove any thing in the drivers line of sight. You can find more information on windshield whimpers on the website, wixapedia.com. Thank you for your time and be thankful for the windshield wipers that work for us, rain or shine!
If the windshield wipers do not turn off in the vehicle, there could be a short between the battery and the wiper motor. It is also possible that the motor is malfunctioning due to the motor not being properly grounded.
The linkage for the wipers could have slipped. If the linkage is not aligned right, then the wipers will not stop at the right spot.
Fuse? Connections? Switch? Wiper Motor? Could be any of those.
Most likely fuse(s). Could be the switch too but probably fuse.