I'm having problems with the stock head unit in a 2001 Cherokee. With the ignition off, the radio works fine but when the car is running the radio is full of static and almost sounds like bad reception. However, the CD player works fine when its running.

I was planning on replacing the head unit but since I found out the radio works fine with the car off I'm not so sure doing so would even fix the problem. Has anyone else encountered this in a Cherokee or other vehicle?

 

could be that you do not have the correct spark plugs, check them, the wrong plugs could be transmitting static. So a search on this - others have had the problem.