Disconnect the cable from the negative battery terminal. Remove the switches for testing. Using an ohmmeter, check for continuity between the indicated terminals of each switch with the switch in each of the indicated positions. If the continuity is not as specified, replace the defective switch. For all except rear wiper washer switch on Xterras and 1998 and earlier Pathfinders, disconnect the cable from the negative terminal of the battery. Remove the knee bolster and steering column covers. Remove the screws retaining the switch to the switch body and remove the switch. The turn signal/headlight switch is retained by these two screws. The wiper/Washer switch is retained by these screws. Installation is the reverse of removal. For rear wiper/Washer switch on Xterras and 1998 and earlier Pathfinders, carefully pry the switch from the instrument panel. Pull the switch out and unplug the electrical connector. Installation is the reverse of removal.