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59 Posts
Discussion Starter #1
Quick question (I feel like such a nubie with this one sorry)

My drivers side head light is very dim and the high bean indicator on instrument cluster is on but very dim. If I turn on my high beams the indicator light comes on full and the head light gets slightly brighter but is still dim.

I replaced the head lights almost two years ago. I assume this just means that the bulb is finally dying but before I replace it I want to be sure there is nothing else wrong.

Kevin (over 5K in mods and I can't figure out a light bulb.....you just gotta love it)
 

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Premium Member
98 Forester...what else
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5,714 Posts
sounds like there's a short in the filament between low and high beams, causing it to short out.
 

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2005 Forester XT 4eat
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27 Posts
I think Roo's nailed it. Long ago I had the very same problem on my 88 4Runner. That was BS.....Before Subaru. :wink:

Chuck
 

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Discussion Starter #4
Would replacing the bulb help or is this problem somewhere in my steering column?

Thanks
Kevin
 

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2004 Forester XT 4EAT
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177 Posts
One vote for the bulb going out. My headlight bulbs in the past has shown their age when they began to dim.
 

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Discussion Starter #7
Just replaced the light and it didn't fix the problem. I wrote to Peaty and my tuner, lets hope this isn't too expensive to fix.


Kevin
 

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The Modfather
2019 Impreza 5dr Sport - Manual
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8,053 Posts
I replied with two e-mails did you get them? I still can't get to this site from work I have to wait till later when I get home and after I do homework with the kids and stuff I can have a look :(
 

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2004 5MT XT
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159 Posts
Here's another possibility: When I drove my new FXT home for the first time from the dealer, I noticed my driver's side lowbeam was so dim it was almost out, and the high-beam iindicator didn't work right (since it was 1 1/2 years ago, the details are fuzzy, but your symptoms sound very familiar). It was the headlight switch. Since the dealer fixed it, I'm not sure where it is (your guess about the steering column is probably right), but I know it took the tech 10 minutes to change it.
 

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Discussion Starter #10
Well it turned out to be the fuse for the headlight. I guess even though the fuse was blown the light still turned on slightly.

It's too bad I didn't check this first seeing how I brought it to the dealer and they charged me $48.00 to change the fuse.

.98 cents for the fuse
3.00 for the hazardous waste removal (you have got to be kidding me)
$45.00 for labor.

I tell you we are in the wrong business -

Kevin
 

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Administrator
2018 2.5i Premium CVT
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18,679 Posts
Wow!

I looked at the wiring diagram and I see how this could happen. Each side has its own fuse, shared by both the high and the low beams. Selection of which beam to light is done by grounding one or the other. This is kind of unconventional when seen from the perspective of somebody who deals with house wiring, as switching the ground is a very big no-no in the eyes of the National Electric Code. But the mantra in automotive electronics seems to be, "if it works, it works."

The high beam indicator is wired across the right side high beam, so anything affecting the right side would also affect the indicator.

I'm still surprised that you could have had a high resistance failure within a fuse. Is there any chance that water got into the fuse assembly? Corrosion on the terminals of any nearby fuses? That happened to me once.
 

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Premium Member
2014 Impreza Ltd CVT
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3,319 Posts
With a blown fuse 8 (Drivers +12 fuse), The passenger both High and Low filamants have +12v.

On Lowbeam, the Low Beam filaments are grounded, the Passenger Hi beam filament passes current to the Drivers side Hi beam thru the high and low filaments to ground. So the drivers side appears on dim.

On High beam, now the 12v goes thru the passenger side low filament to the drivers low then high filament returning to ground.

So on either setting there are 3 filaments in series.

And with the Hi-Beam indicator in parallel with the RH (passenger side) Hi beam filament, it does see some current trickle thru it when in Low beam and current is passing thru the passenger side Hi beam filament.
 

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Discussion Starter #13
Moisture could be a huge issue here, I will check the other fuses near it. In CT we got around 2-5 inches of rain then that night everything froze solid. I just assumed that the frozen water somehow messed up the lights so I didn't do anything until it warmed up again. But with the amount of moisture coming off my shoes with either snow, etc it could have caused a bit of rust to develop.

Thanks - I will be checking everything tonight.

Kevin
 

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Administrator
2018 2.5i Premium CVT
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It would be useful to check for corrision--it did happen to me once--but I spent a good bit of time with the wiring diagram after reading ferret's post, and it looks like he really nailed it. It took me three times through the diagram till I fully comprehended what he had to say. There truly is a horrible sneak path that manifests itself when one fuse burns out, and the results that it produces are utterly counter-intuitive.

We need to produce a bumper sticker sized summary of his analysis and post it in an FAQ here, because this is a situation that utterly defies seat-of-the-pants analysis.

Hey, moderators! How about a refereed FAQ?
 

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13 Work Boot Do it yourself
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583 Posts
Just fixed this problem on one of out cars on Saturday. Seem to me that Subaru wiring harnesses do not like anything but Subaru bulbs.
Do yourself a favor....
Pull out both plugs that are going into your headlights. The male end is the light. The female end should be the socket. Check to see if any of the female holes ar melted.
Thats what created the short in the Forester i was working on. Light would go dim and high beem light would come on real dim...
Just check to be safe. The customer lost all power the night before....
Thanks
Nick
 

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2002 Forester
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1 Posts
The recovery from dimming of my Forester passenger side head light can only last a few miles down each time after the H4 socket has received a wiggle plus a firm push. One thread in this forum have come close to explain that a blown fuse guarding the passenger side bulb is the cause. But I have no fuse to blown when that happen.

A simple follow up have uncovered an over cooked H4 socket. The soft rubber jacket has be come hardened and brittle. I flatten two of three pins of a useless H4 bulb, and test fit it in the female pin, it just fall off the socket by gravity, its that loose.

This is an electrical contact resistance problem. The fault is a sub-standard contact force, as may caused by one or more factors such as, male pin is too thin, Receptical is too relax, material yield under force prematurely.

Cost reduction has driven many parts out source to countries that don't always know or respect of standard compliance. Plus incoming inspection fail to detect sub-standard H4 sockets. All that has never been a problem prior to the new age, out-source out-manufacturing age. Passing sub-standard sockets and light bulbs into our cars. Car owners assume male pins of all light bulbs are compliant to standard and have replace bulb that may be of sub-standard just to save few bucks.

If we can test mate the male and female pins (one pin at a time) we can avoid this problem. Apparently most H4 sockets permits one pin mating test. If not, flatten two of three pins of a useless H4 bulb and test the remaining pin.

I head back to my car the next day after I've replace the burn out H4 socket for a brand new high temperature ceramic socket and can you guess what I have found? Once again, two out of three pins failed that mating test under gravity. You guessed it, I pull out and insert back to socket all female pins with one notch tighter. You likely should fail that mating test when you can separate them with two bare fingers. In my old days, I had to use two pliers in order to part that mating forcefully.

Good luck and have fun fixing.
 

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2002 Forester S with dim driver side headlight

Besides replacing the bulb and even just switching bulbs, I've tried the following to fix this problem:
1) Left head light is dim. It is only getting about 6 volts. On the dash, the bright light indicator is always dimly on. (I.e. classic “sneak path”).
2) Right headlight is fine. Left side fog/day running light, side marker light, and turn signal light all work fine and with the correct intensity. No issues on the right side.
3) Left headlight fuse breaks immediately upon turning on the headlights – regardless of whether engine is running or not. Starting the car without the lights on, the fuse does not break.
4) Left headlight fuse blows even when the connector to the headlight is disconnected.
5).With everything connected and the brights are switched on, the left headlight still only gets about 6 volts.
6) Removing the LEFT headlight relay (and leaving the RIGHT headlight relay in place) changes nothing.
7) Removing the RIGHT headlight relay (and leaving the LEFT headlight relay in place) results in NEITHER headlight working.
8) However, switching the headlight relays has no effect.
9) Unplugging the DRL harness from the DRL resister unit had no effect.
10) As a temporary, disparate fix, I ran a wire from the left light bulb ground prong directly to the chassis. This improved the amount of light coming out of the left light bulb. But, it is still not 100%.

My attempted fixes have been to replace the left light bulb, the connector plug to the light bulb, and the stalk switch. All of which has not had any effect. The connector plug was replaced because the plastic was crumbling apart and unable to make a tight connection with the bulb’s prongs. I haven’t bought new headlight relays since switching didn’t seem to make a difference. The removal of just the right headlight relay resulting in no headlights makes me think there is something wrong in the engine fuse box.

What have I overlooked?
 

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2014 Impreza Ltd CVT
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3,319 Posts
Sounds like you have a pinched wire shorted to ground. Right from the MAIN FUSEBOX to the left headlight connector.

The Red/Blue stripe wire. Follow it back from the headlight connector to the main fusebox. This supplies +12 to the common headlight point. It comes thru the headlight relay and fuse in the fusebox, then exits and goes directly to the headlight connector.

With this pinched or touching ground, when you turn on the headlights, +12v passes thru the headlight relay, then the fuse to GROUND. The weakest link becomes the fuse, just doing it's job.
 

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I had considered that might be the problem. One day I started down that road but chicken out. The thought of cutting into a perfectly good looking harness and probably having to partially remove the fender to trace the wire when I hadn't tried other things seemed foolish at the time.

But given the instaneous pop of the fuse when turning the lights on, it sounds like following the wire to the fuse box is my next move.

Thank you for responding.
 

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2008 Forester XT Sport 4EAT
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I had considered that might be the problem. One day I started down that road but chicken out. The thought of cutting into a perfectly good looking harness and probably having to partially remove the fender to trace the wire when I hadn't tried other things seemed foolish at the time.

But given the instaneous pop of the fuse when turning the lights on, it sounds like following the wire to the fuse box is my next move.

Thank you for responding.
It's easy to test with a multimeter before you pull the harness apart.
Just pull the fuse, attach the multimeter lead to one of the fuse terminals, check for continuity to ground. Repeat for the other fuse terminal. If you have continuity then a sport to ground is your problem and you know which side of the fuse box to start looking in, our you can just run a new wire to replace the shorted one.

Your symptoms do seem to indicate a short between the fuse and the headlight connector though as previously stayed.

Does the fuse blow if you have no headlight attached to the connector and turn the switch?

Sent from my DROID RAZR using Tapatalk 2
 
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