Testing the backup light switch (floor shift auto)? How?

[Corellian Corvette]

Still putting my car back together. Have a 68 Charger Automatic floor shift.

When I put the car in Reverse the backup lights do not come on. The switch I have is of undetermined origin.

I'm sure there is a simple procedure to test the switch (vs. seeing if the wiring is just mixed up somewhere). Can anyone offer suggestions?

Thanks!

[1969chargerrtse]

I have a 69 and the switch is off the trani, runs up to a plug off the firewall and back to the lights.  I think 68 is on your shifter, so remove the console cover, and push in your switch, or jump out the wires that connect?  On the 69 there are two wires, if I touch them together, the lights go on.  Same thing?