OK this topic is covered in great detail in this thread:
You can see many of my posts explaining similar situations such as this one.
But to summarize what you need to do, again lets call your “line switch” Switch 1 and your “load switch” Switch 2 because your names aren’t accurate since both line and load are in the load/Switch 2 box.
Switch 2 needs the master switch:
- Lets establish a few things first:
- Look at your current “dumb” switch and you will find a different color screw labeled Common on the back. That is your load wire to your fixture/light - from the picture that is the Black wire hooked up to your dumb switch.
- The Romex containing the white and red wires hooked up to your current dumb switch is the same wire that goes to Switch 1 and we need to make some changes in this box to make your Aux work.
- As you confirmed above the black wire bundle where the Black wire from this Romex is hooked into is your line from Breaker
- In the picture I see a bundle of white wires behind the other dumb switch. That is your neutral. Put a white pigtail wire into the neutral bundle of wires and hook up it up to the neutral terminal on the master. Also get the white wire that is currently hooked up to your dumb switch and put it into the second hole on the neutral terminal. This will “send” neutral to your Aux switch in the Switch 1 box.
- Find the black wire I asked about that is part of the same Romex as the white and red wires currently hooked up to your dumb switch. Remove that from the black wire bundle and put a wire nut on it as you no longer need it.
- Add a short black pigtail wire to this black wire bundle and hook up the other end to the line terminal on your master.
- Put the red wire that is currently hooked up to your dumb switch into the traveler terminal on your master switch
- Put the black wire that is currently hooked up to your dumb switch into the load terminal on your master switch.
- Hook up ground wire to master switch.
- you can optionally turn on the breaker to verify the switch works.
Switch 1 is your aux:
- Put a wire nut on the black wire as its no longer needed
- Put the red into traveler terminal on aux switch
- Put the white wire into neutral terminal on the aux switch
- Hook up ground wire to aux switch
Thats it.