Replaced my battery. Upon picking up my 1999 Intrepid ES, the speakers emitted a noticable hum, like electrical interferance. When I turned on my factory radio, it sounded horrible. Could not hear music or words, from radio or my 6 disc factory changer, just muffled static. I've been told by the garage that replace my battery that the AMP is gone and needs to be replaced. Is this something I can do, or do I need to take it to an audio dealer. The garage told me the Dodge dealer would charge too much and just to take it to an independent audio installer.

I am assuming that it was working fine before replacing the battery. In that case they need to pay to replace it as it was damage incurred at their shop.
1. Could be that the amp was somehow hit with a power surge.
2. Could be that they moved a ground that now is picking up engine noise, or just doesn't have good contact.
3. Really bad timing and now you're sol.

Either way I would recommend an aftermarket amp anyways.

Is the amp factory? I purchased a car once and the amp that was installed had the GROUND and POWER cables runnung too close together, I took it out and sold it. I took the radio out and put my own system in. Sounds great! 210w blaunkupt radio, all 6 speakers replaced, 2000w amp with 2 1000w subs. Everyone says they can fell me comming a few mins before I get there. Ohhhh Also, don't run the pwr cable near the RCA cables comming from the radio to the amp. That will cause an awful humming noise!

Anyone know where to get the wiring diagram for the FACTORY amp, besides going to a dealers service dept?

Thanks