Headlight Dim

Tiny
MINICH
  • MEMBER
  • 2006 FORD TAURUS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 83,000 MILES
My left headlight does not work on dim. The high beam works. I checked fuse and it is good. I put the fuse from the left low beam in and the right low beam still did not work. I changed the bulb and it still does now work on low but high beam works.

I have no idea where to go from here to find out what is not working.

thanks for you help and time?

John
Tuesday, October 13th, 2015 AT 4:02 PM

39 Replies

Tiny
WRENCHTECH
  • MECHANIC
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Those lights are controlled by a Lighting Control Module. You're going to need an enhanced scan tool to access that module and find out what is going on.

I would check all the wiring and contacts in the meantime.
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Sunday, January 27th, 2019 AT 8:51 PM
Tiny
THEBOSS
  • MEMBER
  • 31 POSTS
  • 2003 FORD TAURUS
  • V6
  • FWD
  • AUTOMATIC
  • 83,000 MILES
Right side headlight dim or wont come on I have replaced the bulb.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
HMAC300
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Check ground for that headlight follow black wire and see if broken.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
THIS IS MIKE
  • MECHANIC
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Theboss
August 20, 2015.

Thank you but I do not see black wire at the bulb plug. Thanks-
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
THEBOSS
  • MEMBER
  • 31 POSTS
Thanks so much it was the black wire broken.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
HMAC300
  • MECHANIC
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If these are auto headlights then scan for codes a local pro will have to do it as it may be a gem module or one of the light sensors. I tcan also be a multi function switch screwing up.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
G.I.DON
  • MEMBER
  • 1 POST
  • 2003 FORD TAURUS
Electrical problem
2003 Ford Taurus 6 cyl Front Wheel Drive Automatic

when pressing the break pedal, the fuel idiot light comes on, the head lights dim and the radio softens. Is this a sign the the battery is failing or that the alternator is failing or both or something different?
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Wow! It's hard to tell from that. It could be something like you described, or it may be a short. Take the car to a nationally recognized parts store and have them load test the battery and check the alt on the car. They will do it for free.

Let me know what you find.

Joe
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
STUPID REQUIREMENT
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Here is the fix:
Disconnect the dim headlight. Cut the center wire (this is ground). Connect a jump wire to the headlight side of the cut wire (leave the other wire disconnected). Run your jump wire to the other headlight. Splice into the center wire of that headlight. That junction should have three wires when finished.
1. Jump wire; 2 wire to headlight; wire to harness.
This works. None of the other posting solutions worked. My vehicle lights now operate as before.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
CARADIODOC
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Brilliant! Instead of repairing the broken ground wire on one side, which would take the better part of ten minutes, you opted for the unacceptable solution of running a wire the engineers at Ford were too stupid to install at the factory.

I taught my students that running a new wire is rarely acceptable. As a supervisor in a shop, I would never allow my customers' cars to be repaired with a cobble-job like that, and you will never get your car back with that type of repair. The original wire became cut on the sharp edge of a metal bracket, or it rubbed back and forth until it grounded out on the body sheet metal, and grounded out, both of which are much more common than you'd expect. We need to identify exactly where that occurred because how long will it be before the next wire in that harness will do the same thing? Every professional who has their customers' best interest at heart would never let a car go knowing a new problem was potentially going to occur in the near future. What part of the country, late at night, will you be sitting on the side of the road?

Cutting the ground wire on the dim head light is not necessary. You're installing a break in a wire that is already malfunctioning because it has a break in it. Also, why would you run to the ground wire way over on the other side of the car? You could have just tapped into the ground wire, ran the new wire less than 12", and bolted it to the body.

There's two other potential problems. The first is Ford is very famous for running the ground wires for multiple, unrelated circuits to a single terminal, then bolting that to the body sheet metal. If that terminal is corroded or loose, the head light current is going to look for an alternate path to ground, and it may find that by back-feeding through the running lights, the washer pump motor, or the horn. That can cause all kinds of conflicting symptoms with elusive solutions. Running a new wire the way you did could make the head light work properly, but it wouldn't address all the other problems. You could end up repairing a half dozen problems, each taking over an hour to diagnose and solve. That is hardly the responsible way to take care of our customer. In my city with over a dozen new-car dealers and about 50 independent repair shops, we are lucky to have only the Chevy dealer still in business who is a widely-well-known crook. We did have one independent shop rip-off artist, but the community put him out of business. Anyone finding this type of "repair" would want to find out where it was done so we could stop recommending them as a reputable shop.

Speaking of back-feeding, the first clue the ground wire was broken was the head light was dim, not out completely. To be dim, some current had to be going through it, but how could it do that with the broken ground wire? The second clue would have been to disconnect the left head lamp. You would have seen the dim right bulb would have gone out. Current goes through the right low beam filament, can't get to ground by normal means, but back-tracks through the high-beam filament, then over to the high-beam on the left side since they're tied together. It goes through that filament, then to ground on the left side. The 12 volts was divided up between three filaments instead of one. That's why the right side is on but less than full brightness. The additional clue is the high-beam indicator on the dash is tied in with that circuit, so it will be on dim all the time.

The second problem is 2003 was just about when the use of unnecessary, complicated, and unreliable computers made their way to lighting systems. On many cars, the ground circuit doesn't go the body any more. The two individual grounds run through the Body Computer first, then to ground, so those circuits can be monitored. In this situation, you'd have twice the ground current as expected on the left ground and 0 amps on the right ground, both of which would set diagnostic fault codes. Legitimate problems would not be able to be detected by that computer. Also, starting around 2000 to 2002, the instrument cluster became the most "intelligent", (complicated), computer on Ford products. My description of the high-beam indicator being on dim won't apply, so that potential clue isn't available.

The bottom line is there is no arguing you may have two properly-working head lights, but the way you accomplished it is not what we want other do-it-yourselfers to think is an acceptable repair. The correct repair is much easier and when we have to bill our time by the hour, is the only way a conscientious mechanic would approach this. We have enough trouble already with a bad reputation for the entire industry. Most of it is undeserved, and we would never back a shop that produced this kind of work for paying customers. To leave your solution unanswered would leave our visitors with the false impression we approve of it. That would do them a huge disservice and destroy our credibility.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
BRAVESTAR1
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I'm back. Working on the same problem. The "mess" I paid for, was crazy. They cut the wires to the back circuit plug, then put in a cheap substitute plug for the light, which had bad wires, that had to be siliconized to keep them in place. Gonna spend tomorrow testing each wire, as I determined. The Driver's side is fine, albeit one of the wires broke, so I found it necessary to replace the back plug with another one, and splice all 6 wires in. Gonna test each one to see what has voltage, amperage, or is just ground, and work from there to fix the passenger side.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Please let us know if you need anything else to get the problem fixed.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
BRAVESTAR1
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Well it turns out that "ground" on the left side (passenger), had no continuity anymore to ground. I'm waiting on a special ring connector to create my own ground wire. (22 awg has too small a ring to use) Not entirely sure what someone did, by attaching a wire to the fuse box, and running it through to the light cone, but I think perhaps it was a way to send extra power into the lights.

I note that the Hi and Lo beam has 12 volts always "on" essentially, and only changes with the amperage when you turn on the lights. Haven't been able to get out there lately, as we're in a period of rain, but since we're all still quarantined here in MA, not much else to do.
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
CAROLINA7919
  • MEMBER
  • 1 POST
  • 2003 FORD TAURUS
  • 146,000 MILES
WHEN I TURN ON MY LIGHTS THE DRIVER SIDE HEADLIGHT IS DIM TRIED PULLING ALL FUSES THEN PUT THEM BACK NEW HEADLIGHT, AND CHECKED THE SWITCH ITSSELF SOUNDS LIKE A GROUND PROBLEM BUT WHERE I THOUGHT ABOUT RUNNING A WIRE FROM PASSENGER SIDE WOULD THAT WORK AND WHAT ARE THE COLORS OF HOT AND GROUND WIRES
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Friday, June 26th, 2020 AT 12:16 PM (Merged)
Tiny
HMAC300
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Red is the hot wire and black is ground it's on top lh side of engine compartment. If that doesnt' fix it and the bulb is good then have it scanned your GEM module may be bad.
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Friday, June 26th, 2020 AT 12:17 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Yep, we are all in the same boat. Can you please shoot a quick video with your phone so we can see what's going on? That would be great. You can upload it here with your response.
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Friday, June 26th, 2020 AT 12:17 PM (Merged)
Tiny
JACK PERLMAN
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  • 2003 FORD TAURUS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 222,000 MILES
Checked all the grounds, checked the socket, cleaned socket contacts. Volts to socket with car off 9.4

I suspect ground problem but can't seem to find any loose.
This car does not have auto on lights.

On person suggested master light switch on this car it has three positions.
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Friday, June 26th, 2020 AT 12:17 PM (Merged)
Tiny
HMAC300
  • MECHANIC
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If this is auto lamps where they come on by themselves it can be the grounds that are shown in the pic. It can also be the GEM module regardless of what system you have as there are 4 different ones. It will need to be scanned for the module. Also check the fuses for corrosion under hood if it is put some dielectric grease on them
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Friday, June 26th, 2020 AT 12:17 PM (Merged)
Tiny
BRAVESTAR1
  • MECHANIC
  • 234 POSTS
  • 2002 FORD TAURUS
Electrical problem 6 cyl Front Wheel Drive Automatic 70000 miles

Alright I read an earlier post about this problem. Basically the passenger side headlight is dim compared to the driver's side one. I tried to bypass the ground, which according to the earlier person's problem seemed to be the case. IN so doing I managed to get the light to brighten up considerably, and turn ON the other light. The only problem was the headlight switch was OFF. Every time I did this, and connected a splice from what I presume was a ground wire to a grounded screw on the frame, I would get a spark from the wire, and the lights would glow bright.

I know this side works, because if you disconnect the light and put it on the driver's side it works just fine, so it's not the light/socket or the $40 housing wiring harness. It acts like it's not getting enough power. We already have 1 car down for motor mounts, I liked to fix this one myself. What can I do here?

Yes both high and low beams are affected and the Daytime Running lights as well. I already tried to change the bulbs to no effect.

One thing to note. On these cars, as I have a Mercury, if you pull the headlight hi/low beam lever towards you, it puts both filaments on (normally) into a sort of hyper mode, I used to use this when I was driving in the super dark of Wisconsin. If I do this same function the dim bulb actually turns off completely, and the other one lights up as it normally would.


https://www.2carpros.com/forum/automotive_pictures/180565_IMG_0944_1.jpg

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Friday, June 26th, 2020 AT 12:17 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
On left front fender near top find wires attached to fender check to see if clean and tight. it is G108

Here is a wiring diagram and a guide to help you get the problem fixed.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

If the ground lights the test light up the ground is bad.

Please let us know what you find. We are interested to see what it is.

Cheers
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Friday, June 26th, 2020 AT 12:17 PM (Merged)

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