[GregK]

Unplug the antenna and see if it's still there. If no, check your antenna and cable. If yes, you have a ground loop or other electrical issue.

 

[GregK]

Make and model of the head unit?
If aftermarket did you use a harness adapter, or how did you connect it to the factory wiring?

 

[GregK]

Sorry for all of the questions... What method did you use to connect the Scosche harness to the head unit pigtails?

 

[GregK]

It's usually because of a bad ground or a bad connection somewhere. Because it only happens on FM I would also suspect the tuner in the head unit.

Did the factory unit also have this problem?

 

[GregK]

In that case I might even suspect a bad coil or spark plug. When you say ticking it tells me that it's only picking up one coil, if it was all of them it would be more of a hum or buzz.

 

[GregK]

Thanks for the help.I replaced a coilpack that i had suspected was bad and the ticking is gone.

Sorry I missed this! Glad to help.