FM Signal Issue - Diagnostic Tips:

B. FM Signal Issue - Diagnostic Tips:

Educational/Public radio stations typically make the best test signals when you are looking for weak FM stations. They are often low power stations.

^ These stations are generally at the low end of the FM broadcast band.

^ They will often carry classical music, or other programs with many "quiet" passages. It is during the quiet passages that noise from the vehicle is most noticeable.

^ It is best to choose two or three of these weak stations and use them each time you perform a test, in order to become accustomed to how these stations sound in "good" cars and what external interference noise is normal.

^ This should be done with the engine both running and not running.

If the customer has a concern about a particular station, be sure to test the radio on that station too. Keep in mind that the noise may only be heard in one part of the band, just as a radio station is only heard on one frequency.

Summary:

^ Select a set of test stations (2 to 3 weak stations or stations that are a customer concern), typically at the low end of the FM band.

^ Note the reception performance of a known good vehicle in the desired locations. Note the presence of any local external noise sources (eg. power lines, etc.).

^ Compare the performance of the concern vehicle when listening to the test stations in the same locations.