I've got a weird issue. On my 00 trans am all the headlights except the far end of the passenger are very dim when in lo beam mode. The far passenger is many times brighter.

When in high beam, the both passenger lamps go bright and the driver side is completely out. Do I have some goofy fuse out, or bad wire somewhere?

 

Well since there are 4 different lights that make up our lows and brights, my guess is you have two different low beam bulbs. One of your low beam bulbs maybe has more resistance than the other causing it to be dimmer.

As for other things you need to check relays maybe.

 

The symptoms sound like a bad ground. When multiple lights wired together have a bad ground, the current will backfeed through the other filaments to ground. When you switch to highbeam the voltage potential is the same on both sides of the driver's lights so the lights go off. The headlights ground to bolts on each side of the radiator support. Check to see if the ground wires are damaged or there is corrosion around the bolts.

 

So I'm baffled, I pulled out the ground bolts on the radiator, cleaned them a little, and added dielectric grease. No change. :-( I also pulled a few of the connectors on the passenger side in case any of them were for the headlights, but all of them seemed very clean. Any other suggestions?

 

Did you check the connectors on the back of the headlights?

 

Yup, I forgot to mention that I replaced all 4 headlamps too initially to try to help fix the problem. I also cleaned out the connectors and put dielectric grease in all 4 of those too. :-(

 

Now you're going to have to start some diagnostics. Get a multimeter and test the voltage at the headlight connectors (unplug them from the lamps). The highbeam wire is light green, the lowbeam wire is yellow, and the ground wire is black. Test the resistance from the ground pin to the ground bolt on the radiator support for each of the four headlight connectors. One of them will show much higher (or even infinite) resistance indicating a problem with that ground wire.

 

Did you check the large gray connector about a foot or so below the headlight? It has wires for the low beam, high beam, and motor. I think it had 5 wires in it, but I don't remember for certain. I had some corrosion in there once. Open it up and check. Follow the wires from the back of the headlight about a foot or two and you'll find the connector attached to a bracket or the front frame rail (I forget which).

 

Didn't see this when I was looking last weekend; all the headlight wires seemed to feed into a thick wire plastic harness and disappear as it went up the passenger side. I'll have to give it another look this weekend when I get a chance to try again. Thanks for the suggestion though!

 

I had the same problem, but reversed. My driver side low beam was bright, and all others were dim.

I had recently replaced the connector on the passenger side low beam because a wire was broken there, so I figured that's where I'd start.

I disconnected the connectors from the bulbs and disconnected the gray connector that ties it all together. I then used a multimeter to test resistance (I figured I'd follow the wire and test resistance at both ends to make sure I didn't mix up any wires or anything).

What I found was that the wires were right, but some how the ground for the low beam and power for the high beam were some how tying together (I didn't touch the high beam power wire in my socket replacing). I didn't have time to tear it apart and figure out how/where they were touching, so I put it all together and figured I'd get back to it that weekend.

Anyway, I didn't use the headlights for a couple days (didn't have anything to do for a couple nights), and I went out to work on them one night and put them up, and they worked like normal. I thought maybe it was a short and that reconnected, but after 10 minutes of wiggling wires around they never dimmed again. I then thought that maybe it was something that happened after they got a little heat to them, but after a couple hours of use it still didn't pop up. I figured if it popped up again I'll tear into it then, but meh, it's working now.

Anyway, if the problem persists, bust out the multi meter and trace wires and see if any are shorted out.