If you have that center red wire removed from the plug, then the ESC are still getting their
power from the main batteries.

Removing that center wire, OR, leaving the ESC switch OFF, just prevents the BEC from supplying
power to the receiver. If you are running the main batteries down, then the ESC may still be
executing a low power reset when the main battery power drops.

The signal and its baseline come through the white/yellow wire, and the ground(black/brown).