dim headlights

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Jan 9, 2007 | 09:15 PM

Rustymuffler

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dim headlights

hey guys, got a problem with my headlights. I've got a 78 f250. My brights work fine but my low beams are really dim. I just replaced my headlights, headlight switch(on the dash), and the dimmer swith on the floor board, and the plugins for the headlights. I was thinking that it could be a bad ground wire, but my brights seem to work fine. any ideas?

Thanks

Jan 10, 2007 | 12:09 AM

fmc400

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From: Austin, TX

Was it doing this before, and then you replaced those things? Or did the problem show up after you replaced them for other reasons?

Jan 10, 2007 | 12:25 AM

Franklin2

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From: Virginia

I would pull the plug back a little bit on the headlight so it still works, but you can probe the terminals with a voltmeter. I would then measure the voltage on the back of the bulb as it's burning, comparing the readings from high to low beam.

If the voltage looks the same, I would suspect that maybe they are aimed a little low. You can check this by putting them on highbeam, and drive up very close to a wall in a level area. Put tape on the wall at the centerline of the two spots of light on the wall, and then back up 25ft. The light should be still lined up with the tape. If not, then adjust the highbeam lights till they line up with the marks on the wall.

When you hit lowbeam, the light should drop down and a little bit to the right.

Jan 10, 2007 | 11:21 AM

Rustymuffler

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lights were flickering on and off

Hey guys, well the reason that I replaced the parts was because after driving down the road for about an hour, my lights would go out then if i hit the brakes or gave a bunch of throttle they would turn back on for a minute or so. The parts were old and I am restoring the truck, so i figured that I would replace all of those parts I listed. I know that the flickering can be caused by a short even by blinker wire, but when the truck is idleing or parked the lights don't flicker on and off. There is no real way for me to test to see if the new parts I put on solved the original problem until I get going down the highway, because like I said it only acts up when I am driving. This is why I replaced the switches. I replaced the headlights because there was a pin hole in one and had collected condensation. I have already adjusted the headlight angles and they appear to be where they need to be, but the low beams are a low glow, I can probably see about 10 feet in front of me when I am parked and it is really faint.

Jan 10, 2007 | 12:32 PM

Franklin2

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From: Virginia

Do the voltage check and see what you get. That will eliminate if it's an electrical problem or not.

Jan 10, 2007 | 12:45 PM

fmc400

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From: Austin, TX

If you do determine it is an electrical problem then I'd venture to guess the problem lies in the method used to connect the wires or the wiring itself. There are wiring diagrams for your truck on Autozone's website. It looks like the red with yellow stripe wire comes off the light switch and feeds the dimmer switch. From the dimmer switch, the red with black stripe wire feeds the lows and the green with black stripe feeds the highs.

Jan 10, 2007 | 04:12 PM

Mil1ion

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Weird condition

Perhaps a bad filament was put in those sealed beams?

I would suggest the Whiter Whites / Brighter Brights headlight up-grade.

https://www.ford-trucks.com/article/...r_Brights.html