Problem with subwoofer on 98 Windstar

I have the JBL audio system in my wife's 98 Windstar. The subwoofer in the back will sometimes not work at all. Sometime it makes no sound, other times it makes a motorboating sound and sometimes it works fine. :screwy: (just like the interior lights that don't alway shut off) :banghead:
I just wondered if any else had this problem and if so what the fix was. I know if I take it to the dealer it will work fine when it's there. :dunno:
Thanks

Judging by the motorboating sound I woill suggest that something before the Subwoofer amp is intermitant. I don't know what the setup is but usually the noise you describe occurs when a connection is broken to the input of an amp.

Just a guess though

Where is the subwoofer at? I would check the connect at the woofer itself then work my way forward.

If it's in the door, then those four contacts on the front of the door need some attention, as they often do :)

Where is the subwoofer at? I would check the connect at the woofer itself then work my way forward.

If it's in the door, then those four contacts on the front of the door need some attention, as they often do :)

The subwoofer module (amp and speaker) is in the rear in the wheel well area. It's part of the JBL audio system option and is hard wired to the front end.
I have had ground problems with this van in the past. I should probably check that out.
Thanks