[stoner60]

I have a 2001 Expedition with a am/fm cassette in the dash and 6 cd changer in the center console. Today all of a sudden the subwoofer started making a heartbeating sound. I opened the panel in the rear and disconnected the sub from the amp and the rest of the system sounds fine.

Amyone have any idea what may be causing this?

Thanks

[gadjet]

short in the speaker wire

[TnMack]

I had a similar problem, trying to locate a replacement subwoofer for my 02 expedition. Got amp from salvage yard, same year, different amp. Ford no longer stocks either part. I may have to go with a custom amp and speaker box.

[opsuper3]

It's called 'motorboating.' Short answer is that the amp has an internal failure. I doubt the parts are replaceable. The last Ford amp I opened was covered in resin. The cheapest route would be to replace it with a junkyard piece as TnMack suggested. If you go with a custom unit, you'll need an isolator, if the amp doesn't have one built in. Crutchfield is usually pretty sharp on what you'll need.