My accessories (power windows/seats, radio..etc) won't work unless engine is running. What gives? In the fuse diagram there are multiple "ignition auxiliary circuits relay" both under the hood and under the steering wheel. Could one of those be it?

 

I'd start by checking all fuseable links and fuses in engine compartment fuse box, then all fuses in drivers compartment fuse box. Swap around a few relays and see if anything changes...but...truthfully...it sounds like an ignition switch issue.

 

All fuses are good. I also checked all the relays that say "ignition auxiliary circuit" and they're good too. Would a bad ignition switch cause this to be the only symptoms? The car starts fine.

 

maybe your ignition switch is acting up, try playing around with that

 

Yes, vehicle has 12.6 battery voltage while off...if battery in good condition...and 13.6/14.2 while running. So, bad/corroded contacts inside ignition switch can be overcome by the voltage increase.

 

Issue resolved. Turns out it was a low voltage battery which was caused by a bad alternator mega fuse. I was essentially driving around on battery only for 3 days...