dim headlights problem

Discussion in 'Electrical' started by neil kaye, Oct 3, 2013.

  1. rubjonny

    rubjonny Administrator Staff Member Admin

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    either that, or replace all the headlight and maybe battery wiring form fusebox to lamps, possibly replace headlight switch, flasher switch and ignition switch as the current has to pass through all of these before it even gets as far as the fuses. fusebox might need changing also, depends where the volt drop is coming from. earth side is at least an easy fix, run the headlight earths straight to battery but as you say this isnt the main issue.

    VW still sell the H4 terminal housings which stand the test of time, terminals to fit them can be had from classic-vw.co.uk. Back in the day I used to get 3 interlocking relay holders from vehicle wiring products, one of them had 3 fuse holders built in which was handy. Seperate fuse & relay per side for dipped beam, and 1 fuse/relay for main beam. you could go for 4 fuses/relays if you like so dip and main beam is fully redundant like factory, but I reasoned that you hardly ever use main beam anyway so 1 fuse/relay should be enough
     
  2. H8V

    h8v Forum Member

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    rj...."VW still sell the H4 terminal housings which stand the test of time"

    Yes, they do, but now I remember I changed my main headlight bulbs to 80/100 watt ones many years ago. That's what caused the plastic housings to deform a bit with the heat!
     
  3. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah that would do it, ebay sells ceramic ones.

    having bulbs that wattage can cause the glue holding the glass lenses on to melt too, so try all the other fixes before you go for brighter bulbs :)
     
  4. GVK

    GVK Paid Member Paid Member

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    Yerp, had 100/80 bulbs in my mk2 once and one of the headlamp lenses fell off!
     
  5. davidut5 Forum Member

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    So i doubled all connections under the hood and the main power to fusebox. Its cranking much faster too.
    I have 14.3v on alternator 14.2v on battery and 14v entering fusebox.
    Tried fixing voltage drop around fusebox but it is everywhere, 13.5v at headlight switch, 13.2v from stalk switch and 12.7v out to the passenger bulb, at the bulb 12.2v. This is with foglights on.
    I will make my own wiring with 2 relays for the headlights.
    I have battery power to y3 and 30 on the fusebox, is that ok?
     
  6. rubjonny

    rubjonny Administrator Staff Member Admin

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    yep that's fine. biggest fix for your volt drop will be a relay kit in the engine bay, as you can see at each switch along the chain you loose a bit and the added advantage is it takes the load off all of them so helps them live a bit longer
     
  7. davidut5 Forum Member

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    I have just made the wiring myself.
    Now thats heaviduty! Still losses about 0.3v to the bulb.
     

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  8. davidut5 Forum Member

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    Did some measuring on a 1996 t4, 14.5v on battery, 11.5v on left headlight and 11.8v right headlight. 0.6v losses to the ground and the rest on positive. It has ce2 fusebox.
    I guess all this old cars need improvements.
     
  9. rubjonny

    rubjonny Administrator Staff Member Admin

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    Yeah with age comes resistance to change. Err, I mean voltage...

    What I did to chase down volt losses was gradually loop out switches from the circuit to see where the drops are. So loop red to black/yellow ignition switch, test. Then loop black/yellow to white/black on headlight switch, test. Loop white/yellow.to yellow on flasher switch, test.

    To check drop on wire from fusebox.to lights loop a wire.from Y spade and stuff into the back of each headlight wire pin on the headlight loom.
     
  10. davidut5 Forum Member

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    Max i can do without relays 12.5v both headlights. I have replaced white/black wire from lights switch and direct ground from headlight plug. There is 13.9 out the switch and 12.7v out the fusebox to bulb. Relays are the best option though.
    1v is still pretty good.
     
  11. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah if nothing else it takes the load off your switches so they last longer, was more out of curiosity than anything else since I was still going to fit a relay kit no matter what :lol:
     
  12. davidut5 Forum Member

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    Washed the engine bay today and after few hours the headlights turned on by themself. :lol::idea:Somehow the relay got power an turned the lighs on! Would be nice if they had switched power.
     
  13. rubjonny

    rubjonny Administrator Staff Member Admin

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    is it still doing it? might be the relays got water inside and shorted
     
  14. davidut5 Forum Member

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    No, cleaned the socket and relay. I have the older relays 53 with metal case, not so good with water.:)
    Now the engine wont start, turned out to be the crank sensor, nothing to do with the wash i believe, hehe!
     
  15. rubjonny

    rubjonny Administrator Staff Member Admin

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    best to grab yourself a waterproof box to put them in for sure wont last long out in the damp these relays. mate of mine just threw his in a sandwich bag :lol:
     

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