With the plug on the start/run-switch removed, measure the voltage on the three prongs inside the wire plug. Only 11A should have +24 volts.
Then put the plug on the start/run-switch back on, and remove the footwell side plug on the PCB box.
With the start/run switch on "off", PIN A (14A) should have 0 volts.
With the start/run switch on "run", PIN A (14A) should still have 0 volts. If it has voltage then, the start/run switch is probably broken.
However, as Cam said, this doesn´t give an explanation for the lights problem rightaway. But one problem after the other. 11A seems to be connected inside the box with 15A, the supply line to the light switch, so there might be a connection.
P.S.: Maybe you should remove the plug on the light switch before you do the above tests, to make sure a possible short in the light switch doesn´t influence the testing. Maybe a short in the light switch is not the result, but the source of the problem.