Start at the firewall. If you use a 10mm socket to unbolt the wires at the back of the fuse panel. Everything will unplug. That plug is actually 3 different plugs snapped together. Rear harness, under hood and front lights. Use appendix E from the back of the -20 manual to verify you are getting to what you have on. Clean all the contacts since you have it apart and if you want. You can probe with a 12 volt source to try hot wiring all of the lights. If nothing else, starting at the firewall has you cleaning all the contacts.
pulling the plug to hot wire or just turning on the lights doesn’t matter. Probing with a test light to the contact inside the light socket needs to be done. If power is there then ground contact inside the socket or the ground wire pointed out in the above post is the problem. No power then start tracing the circuit as the manual says.