Over time, the power window motors in your vehicle can wear out and stop working properly. Some common signs of a bad power window motor are a whining noise, slow or no movement when you press the switch or the window falling into the door frame when you lower it. You can remove and install a replacement motor in your Nissan 300ZX using a few tools. This process is time consuming and should take approximately one hour for each motor you must replace.
Park the 300ZX and shut off the engine. Open the hood and disconnect the negative battery cable from the battery using a wrench.
Open the door that has the power window motor that needs replacement. Remove the Phillips screw next to the door lock mechanism with a Phillips screwdriver.
Remove the screw securing the red light cover at the base of the door using a Phillips screwdriver. Remove the red light cover.
Remove the four screws that secure the door handle assembly to the door cover panel with a Phillips screwdriver. Lift up the door handle assembly and disconnect the power window and power lock cable connectors beneath the assembly. Remove the door handle assembly completely.
Grasp the door cover panel at the bottom and pull outward to disengage the plastic clips within the cover panel. Work your way up from the bottom. Set the door cover panel aside once you remove it. There is a clear plastic sheet beneath the door cover panel.
Remove the four screws that secure the front speaker to the door using a Phillips screwdriver. Pull the speaker away and loosen the screws that hold the speaker wires in place. Disconnect the speaker wires and remove the speaker completely.
Peel away the clear plastic sheet and set it aside.
Locate the two screws at the base of the window glass where the power motor connects. Grasp the window on both sides (inner and outer) and lower it manually until the screws line up with the two holes on the inside of the door frame.
Apply four to five 6-inch strips of duct tape to the outer window glass and outer door frame to hold it in place.
Remove the two screws securing the power window motor to the window glass using a Phillips screwdriver.
Remove the six screws that secure the power window motor to the inner door frame with a Phillips screwdriver. Four screws are located in the center of the door frame along the outer edge of the window motor and the other two are located in the rear section of the door, connecting the power window motor pivot point to the door frame.
Disconnect the electrical connector on the power window motor. Remove the old power window motor.
Install the new power window motor in the same orientation as the old motor.
Secure the power window motor to the door frame using the six screws you removed when removing the assembly. Tighten until secure.
Connect the electrical connector within the door frame to the electrical connector on the power motor.
Line up the two holes on the power window motor arm with the screw holes at the base of the window glass. Insert the screws you removed earlier and tighten until secure.
Remove the tape holding the window in place.
Reapply the plastic sheet to the inner door frame, lining up the holes around the edge of the sheet with the clips around the edge of the door frame.
Reinstall the speaker wires, tighten the screws on the back of the speaker and reinstall the speaker assembly.
Install the door panel cover, lining up the holes around the edge of the cover with the clips around the edge of the inner door frame. Press until secure.
Reinstall the door handle assembly, red light cover and screw next to the locking mechanism. Reconnect the negative battery cable and test the window motor.
