The windshield washer pump on my '99 Suburban is not working. When I turn the control, nothing happens. How do I know if it is a problem in the control or at the pump itself? I haven't checked yet, but I believe the pump is mounted next to the reservoir. Am I correct? I checked the fuse and it is good.

You should be able to check to see if the pump motor is getting +12VDC by connecting a voltmeter of test light to the wire going to the motor and hitting the washer button. If you have juice there, the motor is bad. If you don't have it there it's time to trace it backwards. I don't know on a 99, but on 98 full size trucks the pump is mounted on the reservoir.