A few weeks ago, I noticed my sub randomly get quiet and loud back and forth ONLY while driving. When I'm at a red light or stopped for any reason, it plays a lot quieter than it should be (literally half the volume that it is when it's loud). When I accelerate, it goes back to normal temporarily. For a few days, it did the opposite. When I braked, it got loud, and when I accelerated it got quiet.

This has been driving my crazy. I checked my wire connections at my amp and they were fine. I had autozone check my battery and alternator and they were good. I even checked the voltage myself on my battery and it was fine. They are both stock by the way.

1 more thing I noticed yesterday is my lights dimmed when I rolled up my power windows. It never did this before. I tried it again today and it did the same thing but didn't dim as much.

Does this sound like it could be an amp problem to anybody? I can't figure it out.

Do this for us

Measure your voltage with a DMM at the alt

at the front battery

and in the back

all while idling also.

tell us what you get after that

Edited September 13, 200916 yr by Julian

Do this for us

Measure your voltage with a DMM at the alt

at the front battery

and in the back

all while idling also.

tell us what you get after that

Few days ago I tested it at the battery with my car on and off:

Off = 12.45v

On = 14.73v

Bass on full blast playing Jeezy - Hypnotize with car on = around 13.04v average

I didn't check it at the amp or the alternator yet. Do I use the same setting on the dmm meter that I used at the battery? And can you explain real quick how to do that (black to what, red to what)? Should I also be doing this with my bass at full blast?

Just do it with your stereo off, on your alternator there should be a boot covering a post where your alt puts out + current, and then touch your - terminal of your DMM to the chassis since it is ground, then check your battery so plus to plus and then negative to negative.