Going back to my original post, the DMM fluctuates between .3 and .6A. The test light also flickers, not on and off, but dimmer and brighter. So the draw is pulsating. First thought would be the horn relay, but its disconnected. The voltage limiter on the PCB is an electronic unit from RTE.
I don't have a lot of experience chasing down parasitic drains so I don't know if a pulsating draw is common or if its a clue to identifying the culprit.
Wait a minute. Is this key on or key off? There is very very little in the car that can pulsate. Is it "even" or erratic? Pull the 4 way flasher unit. Does it have a clock? And have you checked for aftermarket stuff like an old alarm, etc?
You need to disconnect the ign switch right at the switch, to find out if there is something wrong internally
And find out if the switch had a "key in" light. There is a timer deal, small cylindrical device with 3 terminals. That would be a suspect.