12V lighting circuit advice please

Discussion in 'The Beginner' started by paul18, Nov 7, 2015.

  1. paul18

    paul18 Funster

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    Been fixing another 12V LED light into my van, but power to that particular area just went. Makes me think its a fuse obviously, so checked with multimeter and yes, no current. However the other lights are working, ie, under hob and rear bedroom area lights, just not the front ones. Cant find a fuse thats blown from my fiddling, and manual no help. I am assuming there must be an inline fuse or another fuse box I cant find somewhere? Can anyone help please, its an 04 Ace (Swift I believe)
     
  2. tonka

    tonka Funster Life Member

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  3. paul18

    paul18 Funster

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    Many thanks, but not quite, my model, Ace range not included
     
  4. paul18

    paul18 Funster

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  5. Chipster

    Chipster Funster Life Member

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    Looks like 10a fuse fed with slate coloured wire.
     
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  6. Khizzie

    Khizzie Funster

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    Yes slate coloured cable from 10amp fuse.
     
  7. Chipster

    Chipster Funster Life Member

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    Drawing should really have fuse numbers.
     
  8. paul18

    paul18 Funster

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    In my fuse box, the fude in that position is a 7.5, but seems intact. I will have to have another look, i suppose i should replace with a 10
     
  9. Chipster

    Chipster Funster Life Member

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    Best way to test a fuse with multimeter on resistance.
     
  10. Khizzie

    Khizzie Funster

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    As a precaution test them all ,you don't know who has had a play with it in the past
     
  11. Bluestar

    Bluestar Funster

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    Just as a couple of thoughts, the lights will be on a loop circuit so a poor connection in the previous unit can cause a problem, also your LED are polarity sensitive so will only work the correct way round.
     
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  12. paul18

    paul18 Funster

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    Thanks, checked all that and multimeter shows no current to first device
     
  13. Bluestar

    Bluestar Funster

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    Ok well if your earth is ok then its back to the fuse box.
    Do you have two way switching i.e. another switch by the entrance?

    Good luck :)
     
  14. paul18

    paul18 Funster

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    No, and some of the other 12v ceiling lights work
     
  15. paul18

    paul18 Funster

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    Really struggling with this one guys. All fuses working fine and all other 12v lights working fine, just no power to or from the one from which I had already sucessfully spurred off 2 little LEDs with no problem. Any other suggestions please
     
  16. Bluestar

    Bluestar Funster

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    So hard when not able to see what's going. on, try a bulb and wire to test circuit rather than a meter, have had it where a poor/dry joint will give a reading but not supply a voltage under load.
    Failing that its a matter of tracing the wiring back to the sauce testing as you go.
     
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  17. paul18

    paul18 Funster

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    Presumably the wire goes back to the previous 12v in the loop which works fine, but short of stripping back fittings impossible to tell for sure
     
  18. andy63

    andy63 Funster

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    If I've read the post correctly and you now have no voltage to the light fitting you have taken the spurs off for your additional lights then you have to trace that supply to source... I know it's stating the obvious but can't think of much else you can do..
    Ta Andy
     
  19. Jonkil

    Jonkil Funster

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    Test the circuit by pos/neutral separately...
    Ie..... Don't just probe it at the light fitting, probe the pos at the fitting using a neutral on the other side of the test lamp taken from chassis/battery and similarly so with the neutral.
    This will eliminate either the pos or the neg and give you less to look at.
    Remember LED's have polarity unlike an incandescent bulb...
    Use a test lamp rather than a multimeter, a multimeter will operate on low mV where a test lamp will take more draw thus eliminating a high resistance problem.
    Don't know if your system is CAN bus ? ..... If so, then it's another kettle of fish.
     
  20. pappajohn

    pappajohn Funster Life Member

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    As already said, leds are polarity sensitive but the installer hasnt necessarily connected all the lights the same polarity.
    Try turning the led over to chech that the wiring is correct.

    Just converted to led in my caravan and half the existing lights were wired backwards.....live wire to wrong pin terminal.
    A conventional halogen bulb will still work but some leds wont.
     
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