FM modulators

If your factory or aftermarket stereo doesn't have changer controls, an auxiliary input, or an available OEM adapter, you can add an external source to your system with an FM modulator (also sometimes called an RF, or radio frequency, modulator). A wireless FM modulator transmits the source signal to your stereo over a standard FM frequency, which you can then tune on your stereo. A wired FM modulator offers improved performance, since it plugs into the antenna input of the stereo.

Power connections can be made at the fuse panel.

Installing wired FM modulators

To install a wired FM modulator, first find a good mounting location. Keep in mind that you will need to access your factory radio through its antenna input, as well as connect the peripheral source to the modulator. Common locations include the trunk, under a seat, behind an interior panel, and in the cavity behind the stereo (see page 5).

Warning: removing your seat could deactivate your vehicle's SRS system.

FM modulators require two 12-volt connections: one to a constant power source, the other to a switched (on/off) source. Since you have to remove your radio to get to the antenna input, you'll have easy access to the power and ground wires in your factory radio harness. If you don't want to splice into your factory wires, you can make the power connections at your fuse panel. Look for empty fuse holders and insert fuse taps. Attach your CD changer's 12-volt wires, which normally come out of the hideaway FM modulator, to the fuse taps. You'll also have a black ground wire that must be secured beneath a nearby screw that makes contact with bare metal on the body of the vehicle.

FM modulators connect between your vehicle's antenna and stereo, allowing you to add a variety of audio sources to your system.

Satellite radio tuner connected via wired FM modulator.

MP3 player connected via wired FM modulator

Following the instructions on your Crutchfield MasterSheet™, remove your stereo from the dash and unplug the antenna from the rear of the unit. Plug the vehicle's antenna cable into the antenna input on the FM modulator. Next, run the output of the modulator to your stereo's antenna input (certain vehicles require antenna adapters — use the online Vehicle Selector or call a Sales Advisor to inquire about a specific vehicle). If this leaves slack in your antenna lead, tie it up so it won't fall down and interfere with the foot pedals.

Install your new component and make all of the audio connections at the FM modulator. Determine which of the available modulation frequencies is least likely to be shared by a strong local radio signal and set it on the hideaway box before you mount the unit (on some models you can change this setting on the fly).

Wireless FM modulators

Wireless FM modulators make it even easier, letting you make connections without removing your stereo or running extra wires. The trade-off, however, is in sound quality. While wireless modulators are convenient, they are susceptible to outside interference and static. Installation is easy — just connect the modulator to your source and plug in its cigarette lighter power adapter.