My 02 F-150 had a HU with cassette and Cd changer in the center console. It started to act up so I replaced the cassette HU with a 03 CD-6 HU. Now the plugs are the same, just hook it up and it works, even with the center console cd changer. The problem is the sound, I am getting no bass what so ever. It sounds really bad. Is there something else I'm supposed to connect to the new HU, or is the new HU is faulty? It seems to work fine other than the audio. Thanks in advance.