OK here we go

At my battery i am putting out 12.6 volts car off
At my amp i am getting 12 volts car off
Connected to all of my cars wires my remote turn on that is plugged into my brothers amp in his car is getting 1.6 volts(amp wont turn on)
Connected to all of my brothers wires the same remote wire that has not changed is getting 13 volts and (my amp works 100 %)

So question is this a bad ground.

If so where do i ground at. my options are some what limited because of deadening that was already installed.

 

A ground is easy enough to test. Find any bare metal. If there is deadening in the way, cut a piece out. Be sure to grind away any material/ paint etc.

 

where are you mounting the amp?? what he said ^ bare metal or if your goin under the seat ground to the bolt that holds the seat down

 

for my ground i sanded down the baby seat hook in the trunk behind the passenger seat