I think this is probably a ground problem, but I'm not sure where to look.

If the headlight switch is off, and I turn on either of the blinkers, the rear blinker works fine, and the front blinker is somewhat dim, and the opposite side front blinker also blinks very dimly. On the instrument panel, both of the blinker indicators and the high beam indicator all blink.

If the headlight switch is in parking light position or headlight position the same three indicators on the instrument panel come on. High or low beams makes no difference. Oh, and the headlights do not turn on. If I try a blinker at that time the indicator for that blinker dims slightly and nothing else happens. This behavior is the same regardless of key position (normally the blinkers shouldn't do anything when the ignition is off).

It's done this three times in the last week, and the first two times it fixed itself. The second time it happened to fix itself while someone was wiggling the headlight switch, but after looking at the wiring diagram I think that may have been a coincidence. Now, the third time, it's been stuck like this for two days.

I took out the headlight switch and tested it with a meter and as far as I can tell it is working fine.
It seems like the headlights and other front lights ground through G104, which is on the inside of the driver's side fender (along with G105). I took those two off and cleaned them, but nothing changed. Also, there are a bunch of other things that use that ground that are all working fine.

What else should I look at?

Thanks,
Ben