did the headlight mod with 2 relays, cut all three wires at the headlight, new wires installed from headlight (12 ga) to the relays one for high beam one for low and grounded directly to battery. have a fused hot wire directly from battery to relay for hot and both relays are grounded on the fender at the same place, i use my hi-lo switch to control whichever beam i need. my hi beams are great, low beams sux as bad as before almost yellow. if i unhook one of my low beam wires at the relay i have a bright light and 12.3 volts at the light, hook both low beams up and only get 5.90 and have yellowish lights and when i unhook either low beam at the relay, i have feed back to the opposite low beam headlight very dim but its there. with all new wires everyplace is it possible i have a bad headlight socket or do i have a bad ground. sorry for the long post

 

sounds like you wired your low beams in series or something

 

is there any way a bad connector could be the problem? everything else is new. any suggestions
thanks

 

If your reading half your normal voltage with both connected your wired wrong is all, if the voltage is cut in half your running parallel, if the amperage is cut in half your running series.

 

have you ever thought about these. http://www.puredieselpower.com/catal...ack-p-271.html
i bought some and they work great.

 

Hey, Gunnie. If you can sketch how you hooked everything up and send it to me, I'll take a look at it and figure out what is wrong. If you wired them in series, they will both be the same brightness (dim) and if you unhook one, they will both go out. I doubt that is the problem. Sketch it out in MS paint or some other software or scan in a pencil drawing and sent it to me if you can. We can figure it out. Sounds like you have a relay coil or something pulling down the other light. Make sure your relays are hooked up right. Those stupid little diagrams that are embossed in the top of them are worthless and hard to read if you aren't familiar.

 

move the ground off the batt. the wiring harness for the head lamps is not grounded to the battery.

 

Dude. It makes no difference whether the lamps are grounded to the battery or the frame of a screw in the dash. The battery is the best place to ground everything, there just isn't enough room for everything. Either way, the voltage reading will be the highest if grounded to the battery. If he moves the ground wire to the frame, the voltage may read a tenth of a volt or so less due to voltage drop because the current must find a path back to the neg battery post where it is grounded right now.

 

I think you've got this backwards...

I agree with Lance, it sounds like you've got them running in series somehow. Relays really aren't my bag though so I couldn't tell you what's wrong there. Post up a schematic if you can and there's plenty of smart folks on here that can check it over for you!

 

Ditto that. Parrallel would be the same voltage on each lamp, series would read 6V or so across each.

Remember, headlights really aren't wired in these trucks as simple as a hot and a ground. They have to use the headlights switch, the multi-function switch (turn-signal flipper) and the ECM and all kinds of other bs to make them work. Did you cut the headlight wires clear of ALL facory wiring? Sound like you are dividing the voltage between the lamps and some other device in the truck. I'm sure when you finally read these posts you will be saying to yourself, HUH? These folks are confusing the crap out of me!!!

Let us know. We're here to help.

 

Pretty sure you got that wrong. Parallel circuits maintain the same voltage. Series circuits do not.

EDIT: Guess everyone else beat me to it. See what I get for not reading the entire thread

 

well this is great , all the replys from you guys, now i'm gonna get my butt kicked for this thread cause of where i got the schematic. let the flames begin.
i hope i can post this without making the mods mad
thanks for your help guys
http://www.ford-trucks.com/article/i...r_Brights.html

 

Well, I don't see anything wrong with the schematic...after a real quick look...but I would imagine you have just grabbed the wrong wire somewhere coming from your switches in the cab. Unlike the diagram shown, the wiring in the cab are not just common switches like the ones shown with one in put and one ortwo outputs. I noticed that the lamps shown are grounded on one side.

I'd try to get a hold of the actual wiring diagram for your truck model and compare it to the schematic you wired up. See if everything looks correct.

 

just wanted to let you guys know i replaced the plugin sockets and corrected the problem.
thks, gunnie

 

FWIW - someone correct me if i am wrong

you should pull the input voltage off the alternator output.

the alternator outputs 14.4 regulated. that is the "high" voltage you want to see at the bulbs.

i "think" most modern alternators sense this voltage at the terminal on the back of their case.

so it makes 14.4 there.
and whatever you get at the battery terminal due to corrosion, poor connections, poor crimping, low quality wire, cable length, insufficient gauge is probably less.

so you want the 14.4 from the alternator, from the source
the battery is self regulating to ~12 volts