2003 Chevy Tracker 2.0 4x4 manual transmission
DRL and auto headlights disabled.
Problem: on low beam setting, it appears the high beams are on. On high beam (dash indicator lights up) it appears to be a low beam.
I unplugged the bulbs and tested at the head light 3 socket plugs.
On low Setting:  I get 1 negative and 2 positives.
On high beam setting I get 1 negative and 1 positive.

To make matters more interesting… the bulbs are H4 instead of the prescribed 9003.

I thought maybe it’s the wrong bulb; but again I tested it with the bulbs unplugged.
And I’ve read that the Tracker is a switched negative (so it supplies constant positive and changes the negative to trigger low or high).  But I’m getting a single negative and two positives.

Ideas?

First - check the headlight fuses - if the Tracker is wired the same way as a Suzuki, there are two fuses one left, the other right, and if one blows, you get weird stuff happening, similar to what you're describing.

Next - remove BOTH bulbs and check each side individually, one wire on each socket should give you +12V (reference battery negative), the other two should give you 0V - once you have that, set your meter for connectivity and check the remaining two wires on each socket for connectivity to battery negative, one in each socket should have connectivity to battery negative for hi beam, the other for low beam - if you don't get this, something is screwy with the way auto lights & DRLs were disabled, and if that's the case, you're kind of on your own, since no one on this side of the internet knows how that was onde.

I checked fuses and they are ok.
When I tested the sockets both headlights were unplugged.
Still scratching my head.
Maybe a diode burned out somewhere?
Or maybe wrong headlight relay or control box??

Let me put it this way - and again, what I'm saying is based on Suzuki wiring - the results you describe are virtually impossible, unless the wiring is damaged - you're going to get identical measurements/readings on both sockets.

I'm also going to point out that the tests I suggested are somewhat different to the ones you carried out, I can't help you if you're not going to follow the instructions and carry out the tests.