ok
80/81a are the back up lamp circuit.. different contacts/circuit , as this is a dual circuit switch..

So, the feed from the ign/k38 go to feed 50 at NSS .. from there, power goes to 50r when in N or P [ through NSS contacts] and that feeds that center terminal I mentioned on firewall.
[ PS . for anyone ..the firewall terminal is another easy to get to test point for checking the starter/solinoid ... if one just brings a wire from bat + to this terminal. the starter will turn. This is a good test circuit break-point for diagnosis as it eliminate all interior switches and wireing by getting direct feed to starter , saving the Tech muchooo time decideing starter part of circuit or NSS/K38 circuit.. there are a few of these terminal spots that are easily gotten to without tearing stuff apart . this is where schematics are priceless and the Best Feature of the CDs... ]

If power at 50 and none at firewall.. has to be NSS
If no power at 50 , has to be K38 or ign sw not feeding NSS at50

Just remember there will be NO power at test lamp until you turn key to start
position... [ making sure you have tranny in Park when doing ANY starter circuit test]
I assume you are jumping the wire connector ends and NOT the terminals at the NSS....