How do I know which wire is which is this old switch?

by ctote   Last Updated June 17, 2018 00:21 AM

I'm replacing the following: enter image description here enter image description here

With this one: enter image description here

But since there's not a white, I have no idea which is neutral. I tried hooking it up as pictured, but only the red wire had any power (and the switch wouldn't work).

This is a GFCI (I think) - its circuit powers the garage doors too. enter image description here

If I put the red in "line" and what was in "line" instead into "load", I at least get the led on the switch powered but the lights don't actually work.

I can confirm at least that (from the picture of the new outlet) the red and "line" wires are in the same sheathing from the wall.

Any guidance would be appreciated!

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