Strange voltage drop to factory amp

[Captain_Awesome_Pants]

Hope someone can help with this. I am having a strange voltage drop on the remote wire (dark green) that goes to my factory amp. I was attempting to use it as a remote cut-on for a camera but went a different direction when I started to detect the drop on the amp ( unit seems to be cutting off and on, music goes from tinny to full).

I checked it with a multimeter and sure enough its going from 12v to about 5v at intervals. I went ahead and cut the cable where I had made the tap and replaced it thinking that was the issue, but it continues. Im thinking its coming from somewhere further upstream.

Anyone have any ideas? Where does that cable ultimately lead up front?

[P3tras]

Amp remote wire goes into head-unit. It is possible that there is something wrong with it But measuring voltage directly at head-unit may be difficult, as amp wire is in the same connector as power and front speaker wires. But connector and pin is quite big. I think you should be able to get voltmeter probe into it. That is pin 9 on connector. Here is pinout when looking from front of connector (wires away from you):
1 2 - - 3 4
5 6 7 8 9 10

[Captain_Awesome_Pants]

Just to followup on this, it does appear to be the head unit not supplying constant voltage. Never heard of that before.

[P3tras]

That is odd. You could use any other 12V lead, but in that case amp will not turn off when you turn off audio (you may hear some static noise). If warranty is still valid, I suggest to bring it for a check.