Hey guys, this is my first post here.  I just bought a '91 4x4 Tracker that's in pretty good shape. 
The headlight low beams work fine, but I have no high beams.  When I turn on the high beams, the hi-beam dash indicator light comes on, but the headlights go dark.  I'm pretty good at automotive wiring, but I'm not familiar with the way these headlights are wired.  I'm accustomed to the setup that has three leads at the headlight.  One is ground, one is for high and the other is for low.
That doesn't seem to be the case on my Tracker.  None of the terminals in the headlight pigtail go to ground, and I think two (maybe even all three, I can't remember) of the terminals have 12 volts on them even with the headlights off.  The wiring diagram in my Haynes manual reinforces that, though it doesn't at all explain how they work.
Can anyone clue me in on this?  I'd like to get my hi beams working.  The Tracker also shows signs that someone has modified the lighting wiring in the past.  I can see the holes in the bumper where aftermarket lights were once mounted, and there are some sort of in-line diodes spliced into the tail light wiring.  Everything except the high beams works just fine, so I haven't looked into it too much yet.  Thanks.

I would not trust the haynes manual, far too many discrepencies, but it is about all i have found. I have been looking around for a FSM that shows the chassis wiring to verify the wiring scheme but havnt found one, looked over on Ack's Faq's and couldnt find anything either.

your head lights do have 2 hots and one ground Suzuki grounds threw the switch the hot for the light is hot all the time when you turn the lights on the switch closes the ground    they are backwards from how you think they should be

Honda uses the same wiring scheme with the lights having power applied whenever the parking lamps are lit and the ground is in the combo switch completing the circuit for the high or low beams. If there is voltage on every wire on the headlight connector(must be removed from the light to check or it will backfeed the ground and show voltage) there is probably an issue within the combo switch.

Hmmm.  I'm having a tough time getting my mind around that.  I understand the concept, but I'm having trouble figuring out how it works, exactly.  The idea of the switch making the ground is simple, but I'm wondering how the combo switch switches between the two filaments using only one ground wire. 
I'm an electrician by trade and I've been doing wiring on cars and motorcycles most of my life.  I'm sure that the answer is simple, but I have had a few drinks tonight.  I'll think about it some more in the morning.  Thanks for the info.

Hmmm.  I'm having a tough time getting my mind around that.  I understand the concept, but I'm having trouble figuring out how it works, exactly.  The idea of the switch making the ground is simple, but I'm wondering how the combo switch switches between the two filaments using only one ground wire. 
I'm an electrician by trade and I've been doing wiring on cars and motorcycles most of my life.  I'm sure that the answer is simple, but I have had a few drinks tonight.  I'll think about it some more in the morning.  Thanks for the info.

Turn the diagram upside down - or - mark the ground as positive - that's all that's different.

Here's what you're accustomed to ...

+12v to fuse, to combo switch, two wires from combo switch to bulb filaments, bulb common to ground.

Here's how Suzuki does it ...

ground to combo switch, two wires from combo switch to bulb filaments, bulb common to fuse, to +12V.

I've omitted the main lamp switch/relay for simplicity, it goes just downstream from the fuse.

Sorry that I mis posted, duh, I dont know why I got it incorrect other than a early happy hour.

there is a single common +12vdc that is always keyed hot and supplies both the high and low beam while there is two grounds that are used to switch between high and low beams on each headlight.

Thanks guys, that's good info.  Armed with a clear head and some good, concise explanations I got the concept all figured out.  The actual problem was even easier to figure out.  Both high beam filaments were burnt out...duh.
In my defense, they both looked fine to the eye.  They had burned out in such a way that a resistance check was needed to diagnose it.
With two new bulbs in the lights, the high and low beams are burning bright.  Thanks again.

I'm gonna tag in a different problem that I have on my Samurai. My drivers side headlight is dim while the passenger side is fine. I haven't looked at the service manual yet but tthought maybe one of the resident experts here might share a simple direction for me to check out / repair.

I did check a different headlight which made no difference. I have also cleaned all of the vehicle grounds previously as enhancement maintenance for an older off road vehicle....

Thanks in advance for any suggestions!!!

Is it dim in both high and low beams?  If so, I'd guess that maybe it was a problem with the 12v supply.  If the headlight schematic is similar to the Tracker (my Haynes manual says that it's basically the same, but Haynes is known to be wrong from time to time), there's a separate fuse for the left and right headlights.  If you haven't already done so, I'd check the voltage present at each headlight.  Unplug the headlight connectors and check from the hot terminals to a good engine ground.  If the dim side has less voltage than the bright side, I'd look for a bad (high resistance) connection somewhere between the fuse box and the headlight. 
Another check that would be worthwhile to do would be to check the voltage available at the actual fusebox.  Remove the two headlight fuses and check from the fuse terminals to ground.  One side of the fuse terminal should be hot with the fuse out and the other side won't be.  The voltage should be a equal (approx. 12 volts) at the hot side of each fuse terminals.  If the dim side is low here, the problem is in the fuse box.
If this doesn't turn up anything, report back and I'm sure that it can be figured out.  Another option that's always a good idea is to wire the headlights through relays.  This would fix your problem for sure and also give you brighter headlights due to less voltage drop at the bulbs.  Most of my vehicles are wired this way.  I've never done it for this switched-negative headlight setup, but it would be simple adapt.

Check also and make sure the correct bulbs are being used - apparently there are bulbs which are physically interchangeable but have different wiring configurations at the base and a dim light in both high & low beams is one of the symptoms reported.

Sorry for not posting a reply sooner... I forgot to check the notify box... dang! It is dim at both high and low beam. I have Halogen headlights and have tried the OEM lights in it as well but it made no difference.

Since I just read this I havent had a chance to look at it more. I will start at the fusebox and check the fuses if there are in fact 2 as indicated. I would be surprised if there is since the Samurai fuebox is soo small, but ya never know.

I like the relay idea but need some help on how to do that. I am all for a cleaner set up and brighter lights for sure....

I had a problem similar to yours Tux, and it turned out to be corrosion in the fuse box where the fuses contact the box. i removed the fuse box and used some acidic soda ( coke or pepsi works) and a brush to clean it out.  Hope this helps.

Thanks man. I will give that a look / try. I haven't had a chance to look at it yet. Crazy Busy!!! I did take some time to travel today and score a hard top, 3 doors, with glass . and a primo targa bar today for $400 samolias....

I see new 1/2 doors being made soon for next spring....   

Other project are always getting in the way .  I forgot to mention... Make absolutely sure it's dry before you re-install the fuse box so it doesn't cause more problems.  It's obvious but I figured i should mention it