Bright, then Dim, Bright again!
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Posting Guru
Joined: Jan 2001
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From: S. Mississippi
Bright, then Dim, Bright again!
My 82 F-150 has a problem.
At idle the headlights are kind of a sickly yellow color, but when you drive it at night, the headlights brighten as long as you are on the gas pedal. let off and they dim.
I've checked the voltage with a digital multimeter and it shows the battery is getting 14.3 volts at the terminals at idle with the headlights, cab lights, stereo and heater on.
what gives?? im stuck here.
At idle the headlights are kind of a sickly yellow color, but when you drive it at night, the headlights brighten as long as you are on the gas pedal. let off and they dim.
I've checked the voltage with a digital multimeter and it shows the battery is getting 14.3 volts at the terminals at idle with the headlights, cab lights, stereo and heater on.
what gives?? im stuck here.
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Bright, then Dim, Bright again!
Check the grounding.
There are few things involving headlights.
Dennis
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There are few things involving headlights.
Dennis
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Post Fiend
Joined: Nov 2002
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From: Memphis, TN
Bright, then Dim, Bright again!
Check the wires IMMEDIATELY off the backs of the headlight connectors. They're subject to being bent a lot, and can break most of the copper strands, leaving you with high resistance there. The terminals inside the connectors can get loose, too. Cheap aftermarket replacement pigtails are only about $3ea.
Posting Guru
Joined: Dec 2002
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From: Princeton, MN
Bright, then Dim, Bright again!
I've noticed that here in MN when it gets downright cold in January i.e. 15-20 below zero, pretty much every vehicle I have ever owned will do that, get noticeably dim when the engine dips to idle RPMs. Honda, Chrysler, Ford. But when my 92 F250 started doing that in warmer weather last year and I asked a couple of mechanics about it (hadn't told them what kind of vehicle it was yet) they asked me what kind of Ford I drive. My dad has borrowed the truck for the last 10 months so I am not sure if it is still doing it but my '01 SD doesn't do it even when it gets bitter cold. I realize I pretty much just rambled there and didn't help you any but it made me feel better. Maybe it will trigger a memory for someone.
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Posting Guru
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From: S. Mississippi
Bright, then Dim, Bright again!
Also when i hit the brakes they dim out even at idle...im not sure what it is, all i know is its charging...where would my grounds be in the engine compartment? i'm really stumped.
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Bright, then Dim, Bright again!
You gotta do what steve said.
As I remember right,they ground out from the headlight pigtail wire.
Dennis
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Post Fiend
Joined: Nov 2002
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From: Memphis, TN
Bright, then Dim, Bright again!
A Haynes manual's wiring diagrams show where all the grounds are.
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Posting Guru
Joined: Jan 2001
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From: S. Mississippi
Bright, then Dim, Bright again!
Update guys.
I've checked the truck some more today, and found out that with the truck running at idle, the battery is getting about 12.4 volts with the headlights on. This is down from a previous reading.
With the engine off and all other accessories, the battery reads a solid 12.9 volts at the terminals.
Am i missing something? i re grounded the engine and body so i know those are good, what else could it be? bad alt?
i've changed the voltage regulator with a known good one and still the same story.
I've checked the truck some more today, and found out that with the truck running at idle, the battery is getting about 12.4 volts with the headlights on. This is down from a previous reading.
With the engine off and all other accessories, the battery reads a solid 12.9 volts at the terminals.
Am i missing something? i re grounded the engine and body so i know those are good, what else could it be? bad alt?
i've changed the voltage regulator with a known good one and still the same story.
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Bright, then Dim, Bright again!
Head for the dimmer switch ,then the light switch.
I assume you checked the headlight plug grounding?
Dennis
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I assume you checked the headlight plug grounding?
Dennis
F.T.E. Assistant Administrator
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"May The Spirit Of Christmas Be An Inspiration To You Throughout The Year"[/font]
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Thread Starter
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Posting Guru
Joined: Jan 2001
Posts: 2,357
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From: S. Mississippi
Bright, then Dim, Bright again!
Once again, another Update!
Well i was looking around under the hood today and noticed a taped up wire coming off the voltage regulator. So being the nosey guss i am i untaped it and found it had another wire twisted in with it and both of them went back to the alternator harness.
I jiggled the wires and the voltage went from a measly 12.4 at idle with the truck running, to a whopping 14.5. Needless to say i cleaned up this little butchering exercise and taped it back up, and put some shrink wrap over it. Needless to say, its good as new and the problem is solved!
thanks for the imput guys, ya'll really helped!
Well i was looking around under the hood today and noticed a taped up wire coming off the voltage regulator. So being the nosey guss i am i untaped it and found it had another wire twisted in with it and both of them went back to the alternator harness.
I jiggled the wires and the voltage went from a measly 12.4 at idle with the truck running, to a whopping 14.5. Needless to say i cleaned up this little butchering exercise and taped it back up, and put some shrink wrap over it. Needless to say, its good as new and the problem is solved!
thanks for the imput guys, ya'll really helped!
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