Audio Systems: kenwood stereo, gmc jimmy, loose connections

Question
This radio is in a 96 gmc jimmy. It plays good on FM stations. If I try to listen to an AM station it will not pick it up with the vehicle running. If I turn the vehicle off it will pick the station up. I dont listen to AM alot but sometimes. So I was courous as to the problem .

Answer
Hi John,
Sounds like interference on AM which is far more susceptible to it than FM which is one reason why FM is more popular.
Check for loose connections especially on the antenna, you can also fit a filter on the power leads, sometimes called a choke. Bad earths can also be a problem.
If you get a whine when running then that's the alternator, crackles is the HT leads/plugs/coil, intermittent pops and crackles can be the set or a loose connection.
Just check it out basically,
Have fun, Peter