I searched for old posts, but didn't see this exact problem. I took my Jeep in for inspection recently, so of course it has a headlight issues I wasn't aware of.

1998 Classic. A couple years ago I did the headlight upgrade. Putco harness, Rampage reflectors and H4 bulbs. No factory fog lights. Has always worked well.

So my passenger light is dim on low beam and doesn't change from dim on high beam. Driver side works normally.

I tried changing bulbs (but that would have been too easy). Also changed the relays with spares I have, no change. Cleaned the ground, no change. Checked all the fuses and all seem to be good. Checked for continuity to ground on the plug and it seems fine. I am scratching my head and can't think of what else to check. I believe the headlight switch is still stock, but wasn't sure how that could cause this problem. The only other thing I can think of is that when I added a rear bumper with tire carrier (Ares make), the license plate led light they included is spliced into the rear passenger tail light. The license plate and tail lights work fine.

If any of you experts have any ideas, I would love to know what to try next. I am running out of days to get this thing inspected and re-registered.

Thanks!

Greg

 

Check the voltage at the lamp first. Follow that wire back to it's source checking as you go.

 

After that, check all grounds. Then check the switch. Then check the harness.

Don't assume just because you replaced it at one point that it's good. I'd be eyeballing that switch, they're notorious for failing. Even with a harnes.

 

Just a follow-up. It took me awhile but I finally tracked it down. It turned out to be the ground that I originally expected, the one from the new harness on the passenger side. It checked ok for continuity from the battery, so I thought it was good. I even cleaned it up some. I had done continuity on the plug before but was probably just listening for the tone instead of looking at the meter. So finally I checked the other headlight and actually looked at the meter, then back to the passenger plug and realized that although the meter was sounding continuity on the ground wire, it was 10 times the resistance of the other light. Then I checked the ground on the original harness and it was fine, so that pretty much cinched the new harness ground as the issue. So I ended up moving it to a better site and presto! Bright headlights!

So lesson learned on using the continuity tone on my Fluke, and thanks to you guys for the advice!

Greg