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Disco 2 D2TD5; upper left rear light cluster, position light failure

Discussion in 'Land Rover Discovery' started by RogerStenning, Feb 8, 2018.

  1. RogerStenning

    RogerStenning Active Member

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    As per the title, the rear left position light has failed. Now, this came back in the MOT as a dim bulb, and when I took it apart to see if there was something obvious, that's when it failed completely.

    It's not the bulb (replacement didn't work either), and it's not the bulb holder (got hold of another and tried that too, same fault), so it's something else, and while I have a hunch, I'd like to hear your thoughts.

    Any ideas?
     
  2. sierrafery

    sierrafery Well-Known Member

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    You'll have to get the multimeter or a control lamp and see what's missing the live or the earth
     
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  3. RogerStenning

    RogerStenning Active Member

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    I got really odd readings that just were not consistent last time I tried :(
     
  4. sierrafery

    sierrafery Well-Known Member

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    Verify with a bulb with wires attached and connected across body and the coloured wire and if it works well this way the earth is the problem, if it dims it means it's bad contact on the feed circuit somewhere and the voltage drops under load even though with the multimeter is OK if you see what i mean
     
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  5. RogerStenning

    RogerStenning Active Member

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    Yep, follow, thanks. Will update once I've given it a try :)
     
  6. brian47

    brian47 Well-Known Member

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    The "position light" is what is usually called the tail light. It's a twin filament bulb, one for the lower power tail light and the other for the brighter stop light.
    The format of these lights can give rise to some misunderstanding regarding the connections. The most important connection is the earth which connects to the body of the bulb and then the pips on the bottom connect one to each filament.
    Failure of the earth can give rise to some apparently inconsistant results. If the wiring is intact, the most often cause of the fault is the connection on the inside of the bulb holder not making a good contact with the body of the bulb. Clean the inside of the bulb holder with a bit of abrasive paper
     
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  7. RogerStenning

    RogerStenning Active Member

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    That was the first thing I did, with some switch cleaning spray. I'm beginning to think the connector may be a bit iffy, but I'll get a chance to have a better look at things on Sunday (next day off).
     
  8. RogerStenning

    RogerStenning Active Member

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    Ah. Missed this the first time around. Not on the pre-facelift D2s (1998 'S' - 2004 '04' plates); these have single filament position, stop, and reversing bulbs, see http://www.allbrit.de/UNI.cfm?PAGE=820006&SPRACHE=EN
     
  9. RogerStenning

    RogerStenning Active Member

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    Just a quick update. It's not the bulbs. It's not the bulb holder. Both have been swapped out or replaced, the same fault manifests.

    Here're the two wiring diagrams, off RAVE.
    [​IMG]
    [​IMG]


    As you can see, the left and right rear tail lamps are shown as twin single-filament lamps, and share each cluster with the reversing lamp and the stop (foot brake) lamp. Each cluster shares a common ground. Each cluster is connected via a four-pin weatherproof connector, and is routed to the light switch on the steering column via a fuse (11) and a couple of headers (0295 & 0707). All of which, before the final connector, are hidden behind various trim panels, housing, or bodywork. Worst case, I have to dig out each darn header to check it in turn. This has the potential to be a complete and utter female hound of a job to work out.

    Sunday is my next day off, so I'll have a look then. First thing I'll be checking is the path to ground, of course, then the voltages. After that, if still no joy, the fuse (it's not that, the other bulbs, Stop & Reversing, work just fine), and by a process of elimination, each of the damn buffers. I just hope it's not the darn loom :eek:
     
  10. RogerStenning

    RogerStenning Active Member

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    OK, conclusion posting.

    It was the fuse.

    I decided to follow the circuit from the fuse box backwards, rather than disassemble things unnecessarily. First thing I looked at was fuse no 11 in the drivers foot well fuse box. It was blown so utterly completely and totally that it'sd almost a textbook example of a blown fuse. a full third of the fuse link in the plastic casing was missing :eek:

    Anyhow, I've replaced the fuse, and the lamps are working again :D

    Sometimes, it's the simple solutions. Have to remember that next time :)
     
  11. sierrafery

    sierrafery Well-Known Member

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    You started this thread the wrong way then cos F11 is not only for the rear LH light is for the front side light and marker(in the indicator) too and you didnt say anything about these only about the rear one cos if we knew that the whole LH side light circuit is dead the fuse would have been the first call :confused:
     
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  12. RogerStenning

    RogerStenning Active Member

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    TBH, I never noticed if those were working or not; I never run on just side lights, I always go straight to position 2 and dipped headlights, which were still working. I dare say that had I noticed the front lights gone as well, I would have automatically checked the fuse first off. Bit of tunnel vision on the fault finding there, I guess. Like I said, simple solutions ;)
     
  13. sierrafery

    sierrafery Well-Known Member

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    The front side marker(in the indicator) should be visible though regardless of the switch's position :cool:
     
  14. RogerStenning

    RogerStenning Active Member

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    Not that I've noticed; are you thinking of the pre-facelift or post-facelift model?
     
  15. sierrafery

    sierrafery Well-Known Member

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    Pre facelift as in this post... the side-markers are in the upper side of both front indicators, they should come on when you switch the lights on
     
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  16. RogerStenning

    RogerStenning Active Member

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    huh. Never noticed. I'll have a dekko next time I go out to the car :) Cheers :)
     
  17. sierrafery

    sierrafery Well-Known Member

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    Probably you have both sides the bulbs blown
     
  18. RogerStenning

    RogerStenning Active Member

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    Could be; I'll have a good look, probably tomorrow :) Thanks for the heads up :)
     
  19. RogerStenning

    RogerStenning Active Member

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    Forgot to mention. Both front side and marker lights are working; no idea what caused the fuse to blow, but I'll be keeping an eye on things. Thanks for the help and advice, all :D
     
  20. Joemac434

    Joemac434 Well-Known Member

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    In theory you should trace the fault that caused the fuse to blow before replacing it otherwise for all you know it's still there waiting to do it again.It didn't do it for no reason