The Nissan X-Trail comes from the factory with an AM/FM radio and CD player. You can upgrade the stock stereo system with an aftermarket head unit from a variety of car audio manufacturers. Once you have chosen the new deck, you can opt for a professional installation, or you can purchase the requisite adapters and tools to do it yourself and save the cost of labor.
Lift the Nissan's hood and remove the grounding cable from the battery. Use a wrench to loosen the bolt holding the cable to the negative battery terminal. The grounding cable connects the battery to the frame of the vehicle. Lift the cable's clamp from the battery terminal and set it aside. Move to the inside of the vehicle.
Grab the lower edge of the dash panel that surrounds the stereo and climate controls, and pull it away from the X-Trail's dashboard. Disconnect the four wiring connectors from the back side of the panel -- two on either side for the headlamps and hazard switches, two at the bottom for the climate controls. Set the panel aside.
Remove the two screws on either side of the factory stereo with a Phillips-head screwdriver. Slide the deck from the stereo dock and disconnect the stereo wiring and antenna cable from the back of the unit. Set the stereo aside.
Insert the aftermarket stereo's installation sleeve into the empty stereo mounting dock. Gather the stereo wiring and antenna cables in the back of the dock and pull them through the sleeve to the front of the Nissan's stereo dock. Connect the stereo wiring connectors to the wiring harness adapter leads. Consult the wiring harness adapter manual for proper connection locations.
Plug the wiring harness adapter lead connectors into the outlets on the back of the new stereo sound system head unit. Insert the antenna cable lead into the FM/AM antenna input on the rear panel of the new stereo.
Slide the head unit into the installation sleeve until it locks into place. Align the dash panel with the Nissan's dashboard and plug in the wiring connectors that were previously disconnected. Press the panel against the dashboard until it snaps back into place. Return to the engine compartment.
Place the grounding cable clamp back around the negative battery terminal post. Tighten the bolt on the cable with the wrench and close the hood.
