Got a dim headlight...changed the bulbs, still dim...obviously wiring, etc.

Anyone had that happen?

 

sounds like a bad ground to me

 

Got soem specs on the truck ?

Year, trim level, does it have auto lamps, fog lamps, did you modify the switch for the fog lamp on, etc ?

Have you do any add ons like taking power from the head lamps for a switch for after market fog lamps ( the relay coil power ) ?

Is it dim on low and high ?

Age of the truck can turn the lense itself milky color, whihc when opaque can cause diminished light output.

All this is under the assumption that they are the factory headlamps, not after market. Is this correct ?

The quick test ( if it is not any of the above ) remove the headlamp, and meter the pins for the headlamp, and see what voltage you get.

Without knowing the year, I can take an educated guess that the ground is the black ( center in the bulb socket ) the low beam is the Dark Blue w/ White stripe and the high beam is Light green w/ Black stripe ( this is 2001 diagram ). Ford is pretty good about not changing this a lot, but it could be different without the MY to confirm.

 

see below

 

When I bought my 2002 f150, I had a similar problem but it was much worse. Sometimes the headlights would work, sometimes they wouldn't, I would hit a bump and one would shut of and the other would stay on, etc. Most of the time they were just really dim. I looked at the light bulb sockets and they were completely fried to the point that the wires were just falling out of them. Whenever the lights would dim, I would have to pull over, pop the hood and shove the wires back into the sockets. I don't know if this was due to an electrical mal****ion or if the previous owner screwed them up somehow. I just went to Autozone and bought new sockets. Around $12 for the pair. You said you changed the bulbs and I assume you would have noticed if the sockets were fried but it's possible that it is the same problem, it just hasn't gotten that bad yet. I would pull the bulbs out and examine the sockets. If there's any evidence of burning or melting, replace them.

 

Yep, the plug itself is pretty melted where the bulb plugs in. Didn't even think to look at that part, and when I changed the bulbs, it was after dark so I wouldn't have seen it anyway. Now what concerns me is what caused the plug to degrade as it did?

 

No need to get a meter then.
That is usually caused by running aftermarket / high wattage bulbs. What actually caused it on your truck..if there are factory bulbs removed and replaced with the same, good question.

Are you the first owner, or is this used ?

 

Like I said, I replaced the sockets for around 12 bucks and I haven't had any problems since. I was also worried that it could be an indication of a bigger electrical problem, but so far so good.

 

No, I bought it used, so there's no telling what kind of lights were in there. I doubt if they were factory.

Thanks, Jiggle...changed the sockets this morning, back to full power...

It was so embarrassing riding around with a dim headlight...i'm sure y'all understand!

Thanks for the help!

 

FYI: When a vehicle has one headlight unusually dim, and the other is brighter than normal, 99% of the time the cause will be found in the ground connection of the brighter bulb.

 

Question, I did the same thing, had aftermarket lights, burned the sockets out, went to autozone and got heavy duty sockets, installed them as the directions indicated, and went back to OEM light bulbs. Problem is now my dims are SUPER dim, and my high beam indicater on the dash stays on dim when the dims are on. The wires didn't match up colorwise but the directions said to match autozone black to ford black, autozone blue to ford green w/ orange stripe and autozone yellow to ford green w/ black stripe. ( at least thats what i think it said.) I have a ford 2003 supercrew 150.
thanks for any help, Jdo

 

I don't really know too much about wiring and electrical, but it does sound like you mixed some of them up. I know the colors didn't match, but when I did it I matched the location of the wires on the old socket to the locations on the new socket. I don't remember the colors, so I'm just gonna make something up. Say that the furthest wire to the right on the original socket was red, I would take to red wire end and match it up with the wire furthest to the right on the new socket. I hope you understand what I'm saying. If you didn't throw out the old sockets yet, go back and check that everything matches up correctly. If you did, well than I don't know what to tell you. Also, since you now have heavy duty sockets, I don't see why you couldn't try putting brighter bulbs back in there and see if that helps the dimness. I'm sure somebody who knows a little more about electrical will come on here and give some more info on the wiring. Good luck.

 

Both problems sound like a bad ground... what happens is that the bulb with the bad ground is forced to find an alternate ground... instead of power flowing from the switch to the low beam filament to the ground, power flows from the switch, through the low beam filament, then through the high beam filament, then back up the wires to either the other headlight's high beam element and to ground, or back up the wiring even further and through the instrument cluster high beam indicator.

-Joe