I have a 2008 infiniti g37s factory sound system works fine but I installed an after market subs and amp was working fine but now my amplifier is giving me the red protect light I replaced the after market amp with a brand new after market amp and it is still putting my amp into protect what might the problem be the ground is good

 

The subs may be blown or you have a wiring issue. Two wires could be touching.

Disconnect the subs from the amp.
Then turn the amp on.
If the issue goes away, the subs or sub wiring is your issue.

If that doesn't work..
Remove the rca cables and then turn on the amp.

Try the remote wire also.

 

It only happens when I turn the volume up past half way

 

You may have too much gain set on your sub amp. If it's hitting its limit then it'll go into protect mode. Do you have your bass turned up so it's real overpowering?

 

What kind of sub do you have?

 

No I have it turn down. It was working good I checked ground connection and the rest of the wiring all looks OK but when I turn the volume past half way it goes to protect

 

Is your sub a dual voice coil?

 

Yes it is

 

Are the sub coils bridged?

 

Yes they are bridged

 

Try disconnecting the sub and then turning it up