Where does the power come from for 4 spd reverse lights

I am trying to get the stupid reverse lights to work on the 1969 Road Runner 4 speed car that I am currently building. The car has a new dash harness, new engine harness and a new tail light harness. I've got all of the other lights working on the car but am having fits with the reverse lights. I tried jumping the connector by the transmission to see if I could get the lights to work but still got nothing. However, if I jumped the wires to some 12v power, they worked. That leads me to believe that there is a short in the power circuit somewhere. I looked at the wiring diagrams on mymopar.com but that just left me scratching my head more.

The lights on the back are grounded through the socket.
The wire is the Violet one that is grouped with a single White one about a third of the way down the left side of the diagram, going to the A through H connector, Terminal C.
The reverse connector terminal C is Violet wire going to the Backup Lt Sw (4 speed) in your case.
The other wire on the switch is the wire that goes to the same A-h connector, terminal D.
They missed tagging the color, but it's White on the other side of the connector.

That White wire continues on the next page to the Radio Conn., half way down the right side.
Also connected to this terminal is the Red-TR wire that goes lower on the page and back over to the first page.
On the first page, the Red-TR wire goes to the end fuse in the fuse block. They are not labelled, but I'd guess that checking the fuses, especially the end on that might be marked Radio, would help!

So, with key ON, you should have power at the fuse.
You should also have a 2-pin Radio connector under the dash with one terminal having two wires, White and Red TR. It should have power with key on.
You should also have power at the White wire at the switch down at the shifter or transmission.
When the trans is in reverse, the switch should be closed, allowing power through to the Violet wire.

That Black wire that feeds the fuse comes from the ignition switch and also feeds the wiper switch. It should have power with the key ON or ACC.

Kind of cute how they tie the radio into the reverse lights. That way, you know something is wrong with the reverse lights.
Same sort of thing they did with the cluster lights. No power to the headlights? No power to the cluster lights either!

BTW, there have been stories about wiring harnesses that are not all wired correctly.
Hopefully, this will give you the info needed to trace the circuits properly.

Thanks, I was able to trace down the problem(s). First, the bulkhead connector on the wiper harness that feeds the circuit was loose. I soldered the wire back in place and now when I jump the loop feed at the bulkhead, the lights work. However, when I plugged the reverse harness back in to the connector and now there are still no reverse lights. So, I went under the car, jumped the switch connection and the lights still worked. Time for a new switch!

New switch arrived from Brewer's Performance and did the trick!