2015 Chevy Duramax battery isolator install?

BBB Industries has free online wiring diagrams. For your vehicle, under Body & Accessories, Trailer Towing, the diagram (WRGC15SILVER102a) clearly show that the Battery positive terminal on the 7 pin trailer connector labeled "A", is "hot at all times".

Coming out of the underhood fuse block this wire is the red with light green wire. Cut this wire and insert the etrailer isolator relay listed above.

Finding a "hot with key on" circuit is another isse.

Chevy has changed the fuse block. Gone are the easily located posts at the front. Any experience with a 2015 or newer?

Dont mind the language here.. But shows you the terminal.

https://www.youtube.com/watch?v=UlEJWaahwpQ

Is the 7 pin going to terminal block stud B in the fuse box under the hood? Thats live 24/7

If so you remove from there and hook to isolator. Then isolator to terminal block.

Then just fine ignition trigger to isolator... Done