I just installed a new head unit, but havent installed the HD reciever that came with it yet. My question is can I connect the ground wire from the headunit and the one from the hd box to the ground wire on the harness. So 2 wires connected to one. Can i do that with the wires that go to the battery too.

 

I don't see any problem with that. But if you pop a fuse then you'll know you're pulling too much current on that hot wire.

 

Exactly.