You need to splice the two wires together:
I don't recall, offhand, which of the two I spliced into the other, so you'll need to get a test light and check which one works when you twist the key to start (this is where the light is 'tested'). That the one you want to splice into the second wire.
The other wire will not light unless it's directed to ground (when the brakes fail), so that's the one that gets connected to the combo valve switch.
I know if I've got this bass asswards, someone will help out (John???).