Alternator or Battery?

Hello,

A couple weeks ago I posted a questions about a similar problem. I still haven't had a fix.

Here's what I got...

2000 Pontiac Grand Am V6

2- Pioneer Premeir 10" subs

1-MTX amp. (425 max W)

4-gauge wire-60 A fuse.

Anyways, I had the whole system working fine for a year with everything but I had 8 gauge wire ran then instead of 4. About a month ago I put in 4 gauge. A week or so later the amp started kicking on and off at a set pattern. Later on I realized that not only was my amp making a delayed flicker, but my car electrical was making a minor flicker. I've been through alternator problems before in a similar setting, however I had the electrical flicker stop once I gave the car some gas. The next day the flicker went away. Then later on that week it just wouldn't work. I turned in the amp to a repair shop (thinking that was the case) and the guy said "there's nothing wrong with the amp at all" There went some money for nothing. So then I got all hands on and tested with a DMM my battery. I wanted to see if my battery was the problem. Tested the battery before and after, no problems. For some reason my car electrical works fine until I turn on the amp. I was wondering if by changing from 8 gauge wiring to 4 gauge-would that be a cause of the problem. Also, would a bigger (higher CCA) battery, alternator, or cap help? I was told that it could be my Power distributor inside my alternator that's the problem. It's pumping out enough to maintain the car fine without the amp. Just as soon as I kick it on the problem occurs. Would a higher-end alternator do the trick? Someone else told me it sounds like my wiring from the alternator to the battery might have a short in it. I don't know. What do you guys think? Any tests or fixes in mind? Let me know

Thanks

If his amp is only 425 watts max he shouldn't be having problems with his alternator. Its a different story if its 425 watts rms though.

Wire the amp to another vehicle for it's power / ground and see what happens. You also need to see what the voltage is like when the battery is under load from the stereo being turned on, if the voltage has dropped to a level below 12 volts the amp may be reacting to this low level.

The other thing to check is the resistance on the ground return, this is very important in a GM vehicle. If you do not know how to do this post up and someone will explain it for you.

Sorry Rob, no I haven't checked the resistance I have a DMM how do you do that? They should be on tight since I just put the new side post in when I bought the new battery less than a month ago. I was starting to think maybe it is a groud issue. But where would it be. I know the ground to the amp should be alright I checked in multiple locations in the back to find a good ground. Yes I also made sure the metal was exposed well by sand papering the surface. Is there any car wiring (ground) that could be shorting out? That might be the case. Let me know what you think.

Thanks

If the amp is mounted to metal, unmount it and place it on a piece of cardboard, does it still work?

To check the ground return resistance, unplug the ground wire from the amp and rest the bare end on the cardboard, do not allow it to touch metal or your hands when you go to do this test, it will throw the reading out the window. Take your meter and set it to read resistance. Ground 1 side of the meter to the - terminal on the battery. Take the other probe and attach it to the ground wire from the amp, if the leads are not long enough, use a length of wire as an extension cable. What is the reading?

Thanks for the answer Rob. Sorry I took so long to respond. I'll have to try measuring that tommarrow.  I'll let you know what's up. I really think you're on to something.

Here's one thing. I have a ground wire going straight from the chasis to the amp. Should I connect the probe on the end where the car chasis is?  While it's on or off the car chassis should I test it? Thanks alot man