.....test

 

Grounds

 

you have a bad ground somewhere. go through your system with a voltimeter or a continuality tester, whatever thats called.

 

.....test

 

.....test

 

just reground them both. re ground the head unit to solid metal somewhere behind the dash, but not too far from the actual head unit and check the amp ground, make sure its grounded to bare metal and or a good ground spot sych as a bolt etc.

 

Reground both of them to the frame each either with it's own or the two together only cut out any common grounds to the battery or frame

 

As the other said check all your grounds. If it is still doing it get a ground isolator.

 

it sounds like there are two ground points that are too close to each other. maybe the amp ground is to close to a blinker ground in the rear of the vehicle?

 

i would try to reground the amp first, probably not the head unit. run the largest wire you can the shortest distance from the amp, but away from other grounds which may interfere, such as the ground for your blinkers or rear wipers, etc.
and of course make sure ur ground is pure metal on metal contact.

 

.....test

 

did it just start after you regrounded the amp?