The Ford Focus comes with a variety of factory stereo systems. Focus owners who wish to make their stock head unit capable of playing media from different aftermarket sources have two options: You can swap the factory deck for an aftermarket unit with a built-in AUX jack for connecting external devices, or you could connect an FM modulator and connect the devices to the factory stereo.
Raise the Ford Focus' hood and loosen the bolt on the negative battery clamp with the wrench. Lift the battery cable from the battery terminal and set it aside. Move to the Focus' interior passenger cabin.
Remove the stock stereo deck to access the outlets at the rear of the unit. Slide the Ford DIN removal tools into the vertically aligned holes at either side of the stereo. Push the tools into the deck until you can feel them lock into place.
Pull the tools in opposite directions (away from the center of the stereo) while pulling the head unit out of the Focus' dashboard stereo dock.
Unplug the two wiring connectors from the outlets on the back of the stereo. Plug the connectors into the leads of the wiring harness adapter. The adapter will allow you to connect the FM modulator to the stereo while it is still connected to the Focus' battery and speakers.
Plug the FM modulator's two connectors into the available leads of the wiring harness adapter. Consult the wiring harness adapter for locations for proper auxiliary connection.
Place the FM modulator's main box in the rear of the Ford's stereo mounting dock. Insert the line-in (an input cable connected to the FM modulator) into the opening between the Ford's stereo dock and glove-compartment.
Slide the stereo into the Ford's stereo dock until it snaps into place within the dash. Remove the Ford DIN tools and return to the battery.
Place the negative battery cable clamp back onto the negative battery terminal. Tighten the bolt on the cable with the wrench to secure it back onto the battery. Close the hood.
