2003 Pontiac Grand Am GT Changing the whole head unit and speakers out, but still try using the Monsoon factory AMP?

A car stereo man myself I have change out a few. I did car install for a while but couldn't move the morning after, takes a short guy for this job. My best advice is decide what you want to do will it be original or new equipment. Either way goto local car audio install shop. Most car installers will help you decide if you really want to up grade. You may find some crabby ones that don't care but most love what they do. I'd stray from the newbie sales guys. Last time I checked some would install a unit you bring without an issue but you could get it for free or almost if you buy a unit from them. Just check around and ask a lot of questions. Leave the security theft device to people who do it everyday, their insured for that stuff as well as setting off air bags by mistake. Your car may also have hidden amplifiers that are in line with your speakers most Factory cars do. If you choose to go with a new system then they can keep them inline are bypass them all together but they know where they all are. 30 years Electronic repair

I have a monsoon factory AMP in my rear wheel area in my trunk. I would prefer to keep the original due to all the security features, and issues that come from changing the head unit, but it has problems. I can't figure out if it's the wiring, or if the head unit itself is bad. All I know is that my car being in park and on accessory things sound fine majority of the time. When my car is started and moving it gets horrible from there. The knobs do the exact opposite of what they are supposed to do example I try turning up the volume, and it goes down instead or I turn the channel to the right and it goes left. My cassette tape used to play just fine, and then the other day it would start ejecting it and saying tape is tight after about 5 minutes of playing or it would cut out and come back on. My speakers I am not sure how to tell if they are bad but every now and then they just pop randomly scaring the crap out of me or they crackle after they make that noise, but then it goes away. I can turn the bass treble and the other one all the way to a negative and it still pops at random. Not sure if the previous owner installed aftermarket stuff and then removed it when they decided to sell it. I do know the security light is on, but my car starts just fine. No codes no problems the stereo isn't locked. I noticed the other day with the AM/FM radio it is very staticy on every channel. I have not messed with anything, because I am unsure what I am looking for to see whats wrong with it. I do have an digital reader that I can check wires with, but not sure what I am supposed to check. I know its better to keep it with the professionals, but I enjoy learning new things about my vehicle. Plus if I break something its on me and not someone else. I have read a lot about this particular thing and its a pain in the A because of the monsoon system.

Hey benn trying to get back to you. Got an email but didn't know how to find you now. First time on here. I read most of what you wrote because I repaired car audio for a long time. Weather it's factory or aftermarket you have a Missing ground not necessarily from Radio to chassis but it sounds like a burnt ground path inside your head unit which I refer to as the traces basically just flat copper wire it will do all those things you said it was doing. You either had a power surge from your amp to your head unit are from you alternator or somewhere in your car that did this or it could have just been a part failure inside your head unit that caused the ground to open. The popping in frying like sound coming from your speakers is DC volts which is actually heating up your voice cool in your speaker. Not good. Either way if you replace the unit just to make sure the grounds are good from amp to chassis radio to chassis so that you don't have any more problems and get your speakers check. If you don't feel like you can do it then the best thing would be to pay a car install guy a little to have your whole system checked out. They will tell you what's working and what's not just so they may be able to say you something

That's what I've been wondering if the head unit itself is bad. It does odd things the lights on the screen only light up all the way at night other then that I can see only half of it during the day. I did notice the harness in the back of the unit is loose and old looking the tape that was on it was so old that it just fell off from me barley moving it. When I accelerate or sometimes when I roll down my window on the driver side the radio does the popping noise or it goes blank and comes back on. How can I check to see if a ground is bad somewhere?

I'm just seeing that you said there was tape on the back of the unit. This could indicate faulty hookup with the wiring or what majority of the repairs i used to do involved resoldering the main plug in the back of the unit. Just make sure no wiring is bear or Touching in the back and you can try to apply light pressure down or up on the plug and see if it corrects the problem. If not then you may still have an open ground inside the unit. If the car battery is shorted out or there's a short in the electrical system somewhere there is a large diode inside the unit that will short out and blow traces on the ground side especially if someone has bypassed the main fuse or has used a higher rating fuse.