This dictionary of wiring diagram abbreviations is for a 2008, not a 2018, but it may help you:

 

Thanks, Johnre. Not complete but at least a start. Where did you get this table. Knowing that might help me find a 2018 version.

 

Based on some other research, try Fuse #26, 10Amp, located in the interior cabin fuse holder. It should be labeled BACK UP in the manual, page 12-10 "Fuses and circuits".

 

Here ya go - spent a little too much time sorting through the service manual... it's sorted by fuse number. Main box (under the hood) is first, followed by Fuse box (inside the passenger compartment).... the circuit number is something subaru references, you don't need to worry about that... some fuses feed multiple circuits. I lumped those all together into the same box so if you look up a fuse number, everything it feeds is in the next column.

the second page is the diagrams for the two different engine fuse boxes.

I marked with asterix notations where something might apply to the FB or the EZ engine (not all fuses exist on both).

it's not designed to be printed, the layout makes it easier to read as a PDF.

Revision History:
Oct 23, 2024 - updated attachment, added starter circuit, unused fuse positions, minor additions
Feb 11, 2025 - added column for relay power, minor corrections
June 30, 2025 - minor corrections, put NO POWER in source power column if circuit cannot be powered

 

Here ya go - spent a little too much time sorting through the service manual... it's sorted by fuse number. Main box (under the hood) is first, followed by Fuse box (inside the passenger compartment).... the circuit number is something subaru references, you don't need to worry about that... some fuses feed multiple circuits. I lumped those all together into the same box so if you look up a fuse number, everything it feeds is in the next column.

the second page is the diagrams for the two different engine fuse boxes.

I marked with asterix notations where something might apply to the FB or the EZ engine (not all fuses exist on both).

it's not designed to be printed, the layout makes it easier to read as a PDF.

Thank you, so much. This is incredible.

 

I added a few things and updated the attachment... unused fuse positions, a starter relay fuse I missed earlier (for push button ignition). not straightforward to reconcile FB vs EZ and push button vs keyed start in one chart. I think I got it right now.