Single Dim Headlight

Tiny
BRAVESTAR1
  • MEMBER
  • 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.


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

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Wednesday, August 4th, 2010 AT 1:26 PM

15 Replies

Tiny
DOCFIXIT
  • EXPERT
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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Thursday, August 5th, 2010 AT 10:27 AM
Tiny
BRAVESTAR1
  • MEMBER
That would be the screw attached to the fender at the top, that is near a strut for the hood? If so, that is the screw I used for ground. That's the one whereby I spliced connections from the wiring harness plug (the part that plugs into the wiring harness for the headlight. It had about 7 wires, and I tried most of em, got sparks most times, and caused the lights to come on good, but without aid of the headlight switch in the car. That one I couldn't figure out. Like i was bypassing the switch, and it worked good, you just couldn't shut it off.


http://www.2carpros.com/forum/automotive_pictures/180565_IMG_0946_1.jpg



If I could add an arrow, I could show you I spliced on the back side, where the thinner wires are. Only one I didn't do was a pure black one, but I assumed it was for the turn signal lights, (white/brown/black wires go to the signal on the light) (Green, Blue, Red go to the headlight) and by then my last splice had fallen apart.
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Thursday, August 5th, 2010 AT 10:48 AM
Tiny
BRAVESTAR1
  • MEMBER


http://www.2carpros.com/forum/automotive_pictures/180565_IMG_0945_2.jpg



This is what I think you mean. Yeah that was tight as can be, and I used that as a ground point to determine continuity and hook-up a new splice for ground. Which then set the lights on, but you couldn't shut em off.
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Thursday, August 5th, 2010 AT 10:51 AM
Tiny
DOCFIXIT
  • EXPERT
Problem is low and high have two seperate grounds. When you add ground to get bright lights what color wire and is it at that plug in pic? Possible Light Green/Black or Red/Black?
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Thursday, August 5th, 2010 AT 11:22 AM
Tiny
BRAVESTAR1
  • MEMBER
There are 3 wires there.
1 is thicker and all black.
2 are thinner one is black with a lime green stripe, the other is plain black.
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Thursday, August 5th, 2010 AT 11:44 PM
Tiny
MERLIN2021
  • EXPERT
My diagrams show different colors, red/blk goes to the DRL relay, Lt Grn/Blk goes to the multifunction switch and grounds through that, and Dk Grn/Orange, goes to he Battery junction box under the hood and is #19 for the right headlamp, You have DRL, but does it have Autolamps?
Principles of Operation

The headlamps are supplied power at all times from the battery junction box (BJB). Ground is supplied through the multifunction switch and the headlamp switch. The flash-to-pass feature has ground supplied through the multifunction switch.

Place the headlamp switch in the ON position.
Place the multifunction switch in the high beam position.

Do the high beams operate correctly?
Yes
REPAIR circuit 13 (RD/BK). TEST the system for normal operation.

No
For LH headlamp, REPAIR circuit 160 (DB/WH). TEST the system for normal operation.

For RH headlamp, REPAIR circuit 161 (DG/OG). TEST the system for normal operation.
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Wednesday, August 18th, 2010 AT 2:53 PM
Tiny
BRAVESTAR1
  • MEMBER
Looks like repair of Circuit 161. Cause with the high beams on and the switch on, I get nothing on the passenger side front headlight. Also if I try the whole pass to flash thing, the light goes out completely.
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Monday, August 23rd, 2010 AT 11:33 AM
Tiny
MERLIN2021
  • EXPERT
Dont forget about how the circuit grounds, through the switch and the mutifunction switch. Common enough problem is the mutifunction, did the PDF I sent have testing for that?
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Monday, August 23rd, 2010 AT 1:14 PM
Tiny
BRAVESTAR1
  • MEMBER
It looks like there is a path to the multifunction switch. We'll try the grounds first, and work backwards from there. A multifunction switch is a lot more expensive than a couple of wires.
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Monday, August 23rd, 2010 AT 6:49 PM
Tiny
BRAVESTAR1
  • MEMBER
I just reread your answer, and now I understand. Somehow I wouldn't have thought there was grounds on the switch itself, given that it works for most other things, and it's a lever in the steering wheel. But I now see that perhaps there might be something to that as well.
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Monday, August 23rd, 2010 AT 6:56 PM
Tiny
MERLIN2021
  • EXPERT
All 3 wires at the headlight are power(hot) grounding is done at the headlight and multifunction switches, If you have the manual test those, if not, after I get back from work, I will look for the info and post it.
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Tuesday, August 24th, 2010 AT 2:30 AM
Tiny
BRAVESTAR1
  • MEMBER
Thanks I have received a few items from you. It does makes sense that all the wires were hot, which is why when I forced em to bypass to ground I either got a shock, or the headlight came on brightly.

I wonder how the headlight itself could ground. After all, it's plastic base is surrounded by a plastic shroud and dome. Kind of a funky system if you ask me. But I just replaced a broken Suspension link tonight on the same car, so we are making progress.

Brett
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Tuesday, August 31st, 2010 AT 11:36 PM
Tiny
MERLIN2021
  • EXPERT
Dont forget used parts at a junkyard. Could save you a lot of money.
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Wednesday, September 1st, 2010 AT 2:40 AM
Tiny
BRAVESTAR1
  • MEMBER
It was the headlight switch, I checked that. It wasn't the multifunction switch, that checked out okay.

It was a wire somewhere along the way from the switch to the light that wasn't feeding power to that side of the light.

I ended up having to pay a place $265 to figure it all out. Fortunately they were also able to fix the dashboard lights which had gone out by then too. I for the life of me, could not find that wire.

These electrical things are the hardest to deal with. I had to give up the ghost, after taking the dash apart, testing many meters of wire, and basically splicing into nearly everything.

Thanks for the help, I will be back next time for the next disasterino.
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Wednesday, October 13th, 2010 AT 2:07 PM
Tiny
MERLIN2021
  • EXPERT
Yep it takes some practice and experience with certain models to get the hang of it. Good luck.
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Thursday, October 14th, 2010 AT 10:32 PM

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