How to Use FM Modulators

The most commonly used and widely know type of FM Modulator is the type that plugs into the cigarette lighter socket. The second type are those that are built into some MP3 players. Both of these methods share the same problem; they sit near your vehicle stereo and broadcast on a frequency that is hopefully not being used in the area. While these types of FM Modulators work well sometimes, other times they can be problematic and frustrating.

The Best FM Modulators require installation in the vehicle. The installation process is pretty simple and the outcome is very effective. These FM Modulators are installed “In-Line” with the vehicles AM/FM antenna.

This type of FM Modulator will block external FM broadcasts on the frequency that you select. Then using that same frequency it transmits it’s own signal straight into your vehicles stereo antenna. This leaves very little chance of interference¬† from local radio stations.

To do this you must gain access to the rear of the vehicle stereo and unplug the antenna cable from the stereo. In most cases the antenna will have a standard Motorola style plug and the stereo will too. In some vehicles an antenna adapter is needed to install an aftermarket AM/FM antenna, two(2) antenna adapters will be needed for this method. Semi-Trucks use the Motorola plug style so you won’t need any adapters.

On the FM Modulator there is an antenna input and an antenna output. Plug the vehicles AM/FM antenna into the FM Modulators antenna input jack. Next, plug the FM Modulators output antenna cable into the back of the stereo in the antenna input jack.

Vehicles that require an antenna adapter for aftermarket stereo installation will need an adapter before the FM Modulator. This converts the vehicles AM/FM antenna plug style into the “Aftermarket”/Motorola plug style and plugs directly into the FM Modulator. The second adapter converts from the “Aftermarket”/Motorola plug style back to the original plug style allowing the FM Modulator to be plugged into the vehicles stereo antenna input jack.

If you would like to find out ahead of time whether you’ll need antenna adapters or not Give Us a Call or visit Click on the “Products” link and then on “Select a Vehicle”. Here you will find a list of parts that are available for your vehicle. Semi-Trucks will not be listed there. Semi-Trucks use the Motorola plug style so you need no adapters to install an FM Modulator.

To get power to the FM Modulator you’ll need to locate the ignition wire that runs into the vehicles stereo. Using a “T” tap to make a splice, attach the FM Modulators positive(+) power wire to the vehicles stereo ignition wire.

The best place to pick up a ground/negative(-) for the FM Modulator is the stereos negative(-) power wire. Once you have located this wire use a “T” tap to splice in the FM Modulators negative(-) wire.

Make sure to run the audio input cables/wire to some handy location in the vehicle. This is where you will be connecting your MP3 Player, Satellite Radio, TV Audio Outputs and more.

On the body of the FM Modulator select the FM frequency that you would like to dedicate to the input of your favorite audio devices. Once everything is all back together and the vehicle stereo is powered on it should be tuned to the FM frequency selected on the FM Modulator.

You should now be able to attach your audio device to the FM Modulator and hear your device playing Loud and Clear through the vehicle stereo speakers.