[Navonod123]

The windshield wipers quit working on my 1994 Chev truck. You can hear the motor trying to run when you switch it on. If you raise the hood and smack it a couple of times with the handle end of a large screwdriver, they'll start working, for a while. W hat do I need to replace or fix?

[mazak]

Usually unhook,the wires going to it,a few bolts to remove it from the fire wall, and unhook the wiper blade linkage.

[CaptainRich]

The windshield wipers quit working on my 1994 Chev truck. You can hear the motor trying to run when you switch it on. If you raise the hood and smack it a couple of times with the handle end of a large screwdriver, they'll start working, for a while. W hat do I need to replace or fix?

There is a GM bulletin out that may address this concern.
The problem is the solder joints are coming loose. You can resolder the loose joints if you want to and have the tools.
Or you can simply bolt on the new board (available from your local GM dealer). No major disassembly required. Disconnect the electrical connector and remove the three screws that hold the cover.