headlight issues

[pecanme]

Hello everyone, I'm a 4 month owner of a 1990 wagoneer and it seems I found my first electrical problem.
My headlights were working fine up until last night. We had a gully washer here in Arkansas last night and I dont know if it has anything to do with it but I got in it this morning at 4:30 to go to work and the headlights were so dim that I had to take my other car. I picked up a new headlight on the way home and its just as dim. With the engine running my harbor freight multi meter shows 13.4 at the battery and 12.8v at the light plug on the drivers side and 12.3 on the passenger. But heres the crazy part! When I plugged in the light on the driver side the voltage goes down to 10.6 on the passenger side and the light goes dim. Why would the voltage drop like that and could the rain mess something up? I'm in no hurry nor capable of getting deep into the electrical system.
Like I said I don't know much about electrical and everything else is working fine so I'm scratching my head.

[SJTD]

The voltage goes down with the light plugged in due to Ohm's Law. V=IR

Voltage drop across a resistor (or wire or series of wires, switches, connections, etc) is equal to the current times the resistance. The meter has a very high resistance so when you check the circuit with only the meter there's very little current flowing so the voltage drop is negligible.

Plug in the light, which draws a fair amount of current, and the drop across all those things becomes significant.

You need to start checking all the connections, including grounds, for corrosion. Check if the switch is getting hot indicating poor internal contacts.

[pecanme]

Thank you so much for the reply!
Ohhh wow I think I understand. Because I didn't have a load on it. The lights were never very bright to begin with so it must be something that got worse.
I started looking around and the switch looks new but one of the metal tabs going into the switch looks dark and melty. Should I replace the switch again?
The plug looks a little burned also.

[dodgerammit]

A good relay setup will take the load off the switch and allow full current to lights.

[pecanme]

I see the "serehill" headlight harnesses being talked about a lot. You even mention it in your signature. Its my understanding that he passed away and I noticed someone named Mass on ifsja is making them. I'm not a wiring wiz but it looks good and others seem to agree. I originally signed up for ifsja to ask him about it but I haven't been approved yet to post or send a message.
Would I still need a switch if I got a harness?

[1979bettywhite]

The harness would be the simplest way to really fix the dim headlight problem for good, and also move the voltage situation out of the cab. Relays are fairly simple to learn and you could really just build the system yourself and learn a bit as you go along. Basically you change the path of your headlight switch providing power to the headlights to the relays "relaying" direct 12V power to the headlight when they are bridged with low voltage power from the switch.

You can use your existing switch. You will need a couple relays for both the low and high beams. Take a look around the net and you can find many videos, diagrams etc for a simple headlight relay harness. There are also plenty of harnesses out there already made up that you can purchase as a plug and play application. Although at times they aren't using the best parts.

I see a lot of people going with something like this:
http://www.lmctruck.com/icatalog/cb/full.aspx?Page=103

Although I do not have any experience with it. It may require some cutting and lengthening of the wires supplied. Ebay has a ton of them as well, just search "H4 relay harness" and you will see quite a few. But once again, quality may suffer with these kits. You may also still have to modify it for your application as well (wire lengths).

I once again think the best bet is to order all your parts and make up your own, solely for the learning experience. The guys on the board will help you along the way.

And last but not least, I have mentioned this a few times before. You keep all of the wiring in place and swap out your stock sealed beam units for an LED application. Basically you buy a new bucket that will accept a separate bulb. Then you would buy a set of LED H4 bulbs. Plug in the new bulbs, install the bucket and you are off and running with a really nice low voltage light.

Although I still recommend the relay route solely for getting the higher voltage draw out of the cab. You can still use the relay system with the LEDs, but they really operate off a pretty low voltage draw, so it isn't really required.

[SJTD]

LED's may be great and draw less current but they aren't a proper fix for dim lights due to corrosion or a bad switch.

[pecanme]

Lots of information here. As a Michigan native I'll never use LED bulbs again. I'm in Arkansas now but when I retire in a few months my wife and I will be moving back to Michigan with family. I used LED lights in my work van back home a few years ago and the shape of the light buckets and lack of heat made for a perfect snow catcher. AutoZone had a switch for about $15 so I went ahead and got one. I'm back in business with ok lights but thanks to you guys I'm now 100% convinced I need a relay harness and the h4 housings I think they're called. As God and my wife as my witnesses I'm just too dumb to put one together. Quality is something I absolutely look at. Lmc kit looks the same as some eBay ones and I'm not really into cutting wires. I'll do some more research. I'm leaning to something with ceramic plugs. My stock plastic ones looked like they got soft before.

[Mass]

pecanme, feel free to pm me here. It took a while for me to get approved over there too.

I can tell you that a relay harness is a very wise upgrade. I'm running the H4 conversions and higher wattage Hella bulbs so for me the ceramic plugs were a must. Sounds like you had a similar issue as me. Before the conversion I was running around with high beams on and still barely seeing.
The wiring in these jeeps are only getting worse with time.

For those who don't know I'm making a harness to sell. When it's ready I'll post in the vendor section of both sites.
It'll have 12 gauge GXL load wire, 14 gauge GXL "trigger" wire, separate fused supply circuit for high and low, sealed Hella 40 amp relays, Delphi (Aptiv) terminals, sealed fuse holder with a spare fuse, ceramic connectors with quality Aptiv/Packard 59 terminals, splices only where 3-way is needed, etc. I refer to it as a "terminal to terminal" build

I'm still waiting for the right gauge terminals to come but I'm very happy with how it turned out.

Be careful what you see out there. As I stated in my thread on ifsja.org I purchased a harness on ebay and It felt so cheap because it was. The whole thing was 14 and 16 gauge wire. A headlamp terminal popped out and wouldn't stay in. They use 50 cent relays. Cheap ring terminals bent and deformed with little effort.
Also be mindful of the harness from "ksuspensionfab" that was mentioned in another post here that fast79chief started ... It's startling but I found the exact harness on ebay for about $10 free shipping. Down to the clear relays, same color wires, split ring terminals, fuse holder, etc.

Just another reason I'm making my own to sell. (see pics)

[pecanme]

I sent you a pm Mass.
Does anyone have a brand or source for the housings they recommend? I'm looking around and I see them from $30 all the way up to $150 for a pair. I also have a new problem where my turn signals are going very slow. What's up with that?

[Mass]

PM returned!

I bought elcheapo ebay ones and they seem decent.

As far as turn signals I'm not 100% sure but have you checked the bulbs? Also could be corrosion in the bulb sockets. I've seen bad wires and connections cause a voltage drop to the turn signal bulbs that was enough to not cycle the mechanical flasher.

Also if you use led bulbs it can cause the same thing.
Check voltage at the sockets and if you replace the flasher I'd go with an electronic one.

[Cecil14]

Generally if you have a bulb out or a short in the turn signal circuit you get fast flashing, not slow. I would check the flasher unit itself under the dash.

Honestly, it sounds to me like you either have a short somewhere, cracked wiring, or (most likely) a bad ground somewhere. I would start at the battery and run down the wiring, checking all the grounds first.


aa

[pecanme]

I just got off the phone with Matt (Mass) to tell him the good news since I went ahead and bought his harness Saturday. I got it this morning and I installed within 30 minutes and I'm very impressed with the quality and my lights are bright again! Thanks again!
I just purchased a pair of Hella headlights from Summit Racing p/n 003177801 along with H4 bulbs. I will update everyone on how they turn out.
Found the right rear turn signal bulb was barely coming on and the arrow on the dash was staying on so I removed the bulb and found gunk where bulb sits. I cleaned it up and is now working better. Still not great its 2-3 seconds on and about 1 second off. I'm going to pick up a flasher tomorrow.
It had me confused too because my other cars will blink crazy fast when a bulb is out. Thanks Cecil!

[Chubbinius]

Pecanme, I ran into a similar issue with my headlights on my 1970...the headlights blinked off and then would come back on again after a few moments, or with a quick cycle of the headlight switch on/off. I thought it might have been water from giving it a good wash, replaced the headlight switch and it was good for a while. Just recently had them do the same thing (while driving around the city one night) and when I reached under the dash, I could feel the headlight switch getting warm.

Figured it would be a nice holiday gift so I ordered up a headlight relay harness plus some new bulbs (combination of LEDs and incandescent) to replace and upgrade the ones installed (brake/taillights, back-up lamps, side markers, and parking lights.

Pleased to hear that a relay plus some clean up on your bulbs had positive results. Hoping the same for mine!