Pull the terminal cable away from the negative battery post, then take out the controls to check for damage. Using an ohmmeter device, look for connection at both ends of each switch in its daily working positions. Replace the switch if you find the electrical connection is not what is needed. To test the switch in the rear wiper/washer from Xterras and 1998-older Pathfinders, gently pry it from the instrument panel, pull it out, and release the electrical connector. Installation is the reverse of removal.