The tail light on the passenger side doesn't work.

You have a short in the cross over wire. Almost all cars and trucks have one main break wire with a second wire "y" in off to the passenger side . You could just wire in a cross over and disconnect the old one.

Your car has lost a ground wire somewhere on the dashboard.

I had a similar issue with my lincoln, it turned out to be the wiring to the socket, was corroded and broken. Since you have done the other things this would be the next plausable place to look. hope this helps

check the fuses as it has a fuse for each headlight if iam not mistaken

Check the ground for your rear lights. It's probably one single ground for all the rear lights, though I don't know that for sure. If it's not a grounding issue, it must be a loose power connection.

the turn signal and the brake light,, not the tail light section use the same filament, so be sure that the bulb is ok, have someone apply the brake,, if it goes on your bulb is fine and you have a different problem than the bulb , on the newer vehicles with the glass end on the bulb and the 3 wires ( sometimes 4 ) the wire gets smashed flat against the glass and doesn't make a good contact , remove the bulb and very gently pull the wire up away from the glass end, see if that works, if not, do the same thing to the socket end

Check the bulb socket. They get really hot and heat can cause the wires to melt solder holding them in place. If you have a test light, probe the socket pins for power,(light switch on). If none on either pin, then probe the wires an inch or so back from the socket. If wire(s) have power replace socket. If not, and even if you find power on the pins but the lamp doesn't work, then also check for a bad or loose ground wire.

You don't really need a diagram, it's simple. If you open both tail light boxes in the trunk you will see at the connector on the bottom a yellow wire in the first position. That goes to the brake bulb. If both tail lights do not work, make sure you are getting power to the driver side light first, if it is not getting power, the passenger side will not work either, they are in line with each other. If it is only the passenger side not working, the bridging wire could be bad.. try jumping it. Also, make sure you are getting power inside the tail light bulb holder. The metal connections can come loose. If there is no power to the driver side tail light it could be the bulb failure relay, that is the round red relay in the rear left side of the fuse box behind the ash tray/ cigarette lighter below the radio in front of the shifter. You should be getting power to the third brake light in the rear window...that is a different circuit and will not be affected. Try changing out the bulb failure relay, it supplies the power to the tail lights.

Over time corrosion can accumulated and rust out a tail light socket and render it non-functioning. Yes it can be replaced and in your case for about $6.00. You can find these at most any auto parts store.

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It sounds like a ground wire problem. Try to trace the ground wire from the passenger side. Look for a broken wire or a corroded ground connection.