Possible wiring issue or interference?

I recently installed an amp to power my four speakers and a Pioneer head unit. For some reason when I turn my windshield wipers on, it interferes with the sound.

I'll be listening to my CD and if I turn the wipers on, everytime they move (or activate) it cuts into the sound, like it stops for a split second.

I don't know where to begin, so if someone could help me and let me know if this is a ground issue, short somewhere, or intereference, I would appriciate it.

Thanks!

The power wire, acc wire, and ground wire from the head unit I connect all from the units wire harness to a harness adapter, and plugged that into the stock harness.

I installed the amp under the passenger seat so I ran the wires under the carpet and along the center console to the back of the head unit.

Also, I used StreetWire ultra cable speaker wire and Streetwire Zero Noise 2 RCA patch cables.

I will try a better ground but just for you rinformation, even when I had my stock radio and no amp, when I would open or close the windows, the headlights would dim also.

Is the cars ground system bad? Or is it an issue with the battery and or alternator? Thanks.

I will try a better ground, I haven't really noticed the lights dim during playing, but when I use the wipers it cuts into the sound.

And when I had a stock radio and no amp, the headlights would dim when I opened or closed the windows. Not sure if thats a problem with the cars grounding system, battery and or alternator.

Looks like you've answered your own question and pinpointed the cause of the problem.  Start with a complete refurbishing/cleaning of the existing Big 3 under the hood.  Battery to chassis ground:  disconnect, clean with baking soda/ water, sand chassis at ground point.  Leave the neg battery cable disconnected while you tinker with the rest of the wiring.  When all is done you can reconnect to the battery.  Clean battery posts.  Inspect the wiring from alternator to battery, including the connection at the fuse panel.  All connection points must be disconnected, cleaned, sanded and reconnected.  Verify the voltage of the battery by testing;  it should read 12.6 volts.

When all is reconnected, read voltage at the battery terminals while the engine is running in idle;  it should read 13.5 volts or better.  If the battery is bad, replace it.  If the alternator continues to produce less than adequate power, you will have to replace it.  As it is now, it is not performing as well as it should with the stock car accessories....so something is either bad, going bad, or worn out.  You cannot use additional audio accessories under these conditions.

Thanks for the input guys! I think I found the problem. I think you were right on target about the voltage drop stevdart.

Before I installed my aftermarket headunit I had the remote turn on lead from the amp connected to the 12V acc wire from the radio harness as there was no antenna/remote turn on wire.

I went back and unhooked it from the acc wire and connected the remote turn on lead from the amp to the back off the pioneers remote turn on lead, and it solved the problem!

It stopped doing it so I think that solved it. I will though go ahead and get a grounding kit for my car as other owners have said the ground system isn't that good, and it should help with the dimming of the lights.