Subaru Forester Dim Headlights

Discussion in 'Import Vehicles' started by jd, Feb 13, 2017.

  1. jd

    jd Hero Member

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    Please fill out the following to ask a question.

    MAKE:Subaru
    MODEL:Forester S
    YEAR:2002
    MILES:175000 miles
    ENGINE:2.5 Boxer Four
    DESCRIBE ISSUE....Dim Headlights! Driver Side dimmer than Passenger Side. The High Beam Indicator in the instrument cluster lights, dimly, on Low Beam. It becomes bright like it should on High Beam. We just checked and the Daytime Running Light feature does work. And when it's running with DRL on as it should be, and we turn Headights ON, they DO get brighter. So I know it isn't stuck in DRL mode. Just dim... I'd suspect a bad ground, especially with the glowing indicator.
    Ideas? What Color is the Headlight Ground Wire, and Where does it ground to the vehicle?
     
  2. nickb2

    nickb2 Wrench. I help when I can

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    Here you go. This following pdf should answer your question.
     

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  3. nickb2

    nickb2 Wrench. I help when I can

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    Here is a snapshot of ground locations, focus on starter ground first, most likely to be suspect. Then proceed to ground point #2.

    That ground usually provides current for right and left.

    So check that out, post back if you still haven't figured it out. I will provide more details.
    Screenshot (51).png
     
  4. jd

    jd Hero Member

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    :fixed:WOW!!! I'd have to print all that out and try to trace to ground. But, thank goodness it's :fixed:!! The radical step we took was stop by the auto parts while on an errand run, and get a New Bulb. I cleaned the contacts and tried to spring them a little tighter. Packed with grease (Vaseline), but I wonder if there wasn't also a defect in the bulb.
     
  5. jd

    jd Hero Member

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    My excitement is short lived. The lights come on in DRL mode with engine running and parking brake off as they should. But the High Beam Indicator in the Instrument Cluster come on, and stays on whether the lights are on in DRL, Low, High, or Passing mode(s). The lights seem to be the brightest in LOW beam, appear to actually dim in HIGH beam. Maybe they fall back to DRL.

    Owner replaced the second socket (driver side, passenger side previously replaced), so I'm not 100-percent certain something isn't crossed.

    I printed the diagrams, and am pretty sure the vehicle switches both Power AND Ground, with Switches and Relays. Is that true? If so, then I can't do what I hoped I could. That hope was to tap into the ground wire from one of the sockets, and ground it to a new, extra, location. But if Ground is also switched, then I don't think I can do that.

    Also noticed there's a Diode. I don't know what role it plays, but I'm sure that if it's failed shorted/leaky or open, odd things are going to happen.
     
  6. Mobile Dan

    Mobile Dan wrench

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    After looking at the schematic, I would remove connector B102 from Daytime running light relay. Then ground Yellow/red wire (connector position 1). Both low beam lamps should come on.....are they equally bright?
    But first...locate MB-2 M/B FUSE NO. 9 and MB-3 M/B FUSE NO. 8 and remove both of them (at the same time!) and check for power at the sockets that they plug into. (and of course, check them visually to see if one is blown)
     
  7. jd

    jd Hero Member

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    I think I can do this tomorrow. Just taking a quick poke at it today, seems like about all it actually had was DRL.

    Am I correct that, on the lamps, Terminal 1 is Low, 2 is High, 3 is Common/Ground?
     
  8. Mobile Dan

    Mobile Dan wrench

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    To define headlamp connector, I would say it this way....term 3 supplies power for high and low. If term 2 is grounded, high will illuminate. If term 1 is grounded, low will illuminate.
     
  9. jd

    jd Hero Member

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    Tied up too much of the day with tire problems. Screws in RF tire one one vehicle and RR on the other. Two hours at Sam's Club to repair two tires and rotate tires on one vehicle! No car in the shop area but ours, FIVE "techs" milling around, 1-3 doing a little something.

    Anyhow,

    Diagram shows a High Beam Relay that's SPST and a DRL Relay that's DPST. I find only two SPST relays designate Left and Right Headlight, each with a 15A fuse. I don't find a DRL Module or a DRL Relay.

    Turning Low Beam on, the lights appear about like DRL, but in High Beam, the lights DIM. High beam Indicator glows dimly in DRL, Low, and High. I think it's trying to burn BOTH filaments in High. That would explain how they went years without needing a headlight bulb. Now, three bulbs AND two Sockets in about a year.

    Today, I pulled the 15A Fuses and the two Headlight Relays, one at a time. Tomorrow I'll disconnect one Bulb at a time and see if that generates any changes.
     
  10. jd

    jd Hero Member

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    :fixed: Nothing was actually wrong with the Subaru! What WAS wrong was the owner replaced the passenger side headlight bulb Socket, and wired High Beam correctly. BUT!!! Low and Common were reversed. So... DRL was OK. Not sure if LOW was actually Low or dimmed to be DRL. Fog lights would not come on, and the High Beam Indicator glowed. In HIGH, or Passing, lights actually dimmed, because High was getting its Ground through the Low Filament.

    The 9003/HB2/H4 headlight bulb is pinned out this way: Orient it so one terminal is horizontal at Noon. That's LOW. One terminal is vertical at Nine, and that's COMMON. Usually Common is Ground but the way this car's wired, Common is Hot, and Low and High get grounded. The remaining terminal is vertical at Three, and it's HIGH.

    I'd expect the Nine and Three terminals to be Low and High, and the horizontal Noon terminal to be Common, but not so.

    Anyhow, DRL works. LOW works, and allows Fog Lights. High and Pass work as they should, and when working, Fog is off. Indicator is Off in all but High/Pass, no Glow in DRL or LOW. :fixed:

    This Forester is all the more confusing because High is Red on both sides, and Low is Yellow/Red on both sides, but Common is Blue/White on the Right and Red/Blue on the Left.

    Anyhow, :fixed: Thanks everybody!
     
  11. Mobile Dan

    Mobile Dan wrench

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    Yes, the Forester headlamp circuits work backwards from the way things are usually done. There is a certain ranges of years that GM trucks front lights were "backwards" and threw my diagnostics for a loop.
     
  12. JackC

    JackC wrench

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    Nice work. It is very confusing and frustrating dealing with another persons error. Especially when you have no idea that it might be wrongly wired.
     
  13. jd

    jd Hero Member

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    We have a Haynes Manual #89101 Legacy and Forester 2000-2006. It contains Headlight Wiring Diagrams for "Early" and "Late" models. NickB2 sent a third diagram. Of the three, it was the closest to what I saw actually working on the car. None of the three really matched what I was seeing, but the one from BAT was the closest. At least the wiring colors at the sockets matched! That, and the "anatomy" of the 9003/HB2/H4 bulb. Which filament is High, which Low, and the pinout I posted above, were keys to fixing it.

    And... I didn't observe a Cardinal Rule: Go Back to the Most Recent Work Done! See if the problem starts there...
     
  14. JackC

    JackC wrench

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    But you got it and did not give up. Congrats.
     

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