Thanks for the tips, I was thinking about trying some things with the
light sockets, like switching the bulbs out from L to R, etc. Now I'll
also check the resistance to ground and clean the contacts in the
I'm no auto electrician, but from what you've described I think the
side of the circuit that is being watched is the load side, before the
bulb. Naturally, the schematic just indicates a ground after the bulb.
All the graphic display circuitry, which consists of a couple of
splices and a resistance wire between them, is before the bulb inline
with the hot wire.
It helps a lot to understand how something was designed, at least in
theory, when it starts blinking at you. Thanks!