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lights under exterior handles

Discussion in 'A4/S4 forum(B5 Chassis)' started by boost-addict, Oct 13, 2013.

  1. boost-addict
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    boost-addict Member

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    ok so been wanting to do/ask this for some time,

    now ive used a multimeter at the front centre interior light panel and cant seem to find the source that turns the lights on/off inside the car when the car is locked/unlocked.

    it seems that the same positives go live when the car is unlocked, the door is opened or the switch is turnt on.

    so im a little stumped as i cant find the source power which would auto turn and turn off the lights as and when the car is locked and unlocked

    were can i find the power source that turns the interior lights on so i can use a relay to switch the lights under the handles

    desired effect im after

    leds2.jpg

    i have searched and theres no real guidance or even any real discussion on the matter
    #1
  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    It might be a switched ground and a permenant live?

    Have you looked at the wiring diagrams?
    #2
  3. boost-addict
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    boost-addict Member

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    to be fair no. i dont having diagrams. i didnt notice multiple earths on the plug
    #3
  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I'll dig them out tomorrow for you.
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  5. boost-addict
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    boost-addict Member

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    ah ok cheers. seen alot of people say its cheesy, but i think it would make a nice subtle mod
    #5
  6. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Sure marks done this to his !!
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  7. Oranoco
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    Oranoco Active Member

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    I like it, let me know how you get on. I was planning on doing puddle lights under my mirrors but not got round to it yet.
    #7
  8. boost-addict
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    boost-addict Member

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    Whats his user name.?

    Btw i struggled to find a wiring diagram on interior lights Ill get a Haynes manual and have a read over lunch at work tomorrow

    Maybe even test the circuitry while i have a manual in front of me
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  9. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Byzan BAHons
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  10. boost-addict
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    boost-addict Member

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    No one under that name
    #10
  11. boost-addict
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    boost-addict Member

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    Never mind found him. Wasn't in the member search!!??
    #11
  12. boost-addict
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    boost-addict Member

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  13. boost-addict
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    boost-addict Member

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    ok so....

    the brown and white wire goes to 0.39v when the car is unlocked. when locked the wores goes 12v.

    with all the panels and carpet out i noticed a relay (382) clicking when the car was unlocked, and clicked when locked and the lights went out, it would also click when the lights dimed/timed out,

    so removed the relay and stuck the probe in there and got exactly the same, 12v when car is locked and pretty much 0v when its unlocked, the removal of this relay didnt stop the lights coming on and off as i locked/unlocked the car.


    so if the brown/white wire comes from the auto dimming control for the centrl locking then how does this control the lights if it goes 0v when the car is unlocked and the lights come on,

    can you run a relay so it switched on, when the 12v supply is cut? guess i need a single pole double throw relay

    so when the power goes to 0v (car unlocked) itll close the relay making the lights come on
    when the car is locked the relay will operate and cut the power from the lights under the handle.

    but not sure if you can have a relay permanently on for long periods of time.
    im sure this is how the 382 relay is operating
    #13
  14. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    That relay you've found cuts power to the interior illumination after a period of time when the car is off, so you dont drain the battery if you leave a door open etc.

    Its not what your looking for.

    The CL module turns the lights on, you need to find the feed the CL module uses, it will be a switched earth.
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  15. boost-addict
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    boost-addict Member

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    yer i guessed i should be looking at the cl unit, any idea were its located, i looked under the dash but couldnt find what i was looking for

    then need to know what wire to feed from.

    then i suppose i need to run a perm live to a relay and have the earth switch the relay?
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  16. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    yep. Its in the boot cubby hole.

    I forgot about the diagrams, will get them tomorrow for you.
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  17. boost-addict
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    boost-addict Member

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    thats ok, will the one i posted help me?

    also while im there, is the horn in the same place?

    [​IMG]
    Last edited: Oct 14, 2013
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  18. boost-addict
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    boost-addict Member

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    Any luck?
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  19. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Done it,

    I have my handle lights and puddle lights so they illuminate when the interior lights are on, crude but effective. I unlock the car they come on, and dim out when ignition is switched on. If i want to test or show off, i switch interior lights on
    #19
  20. boost-addict
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    boost-addict Member

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    But i want the lights to behave the same way. Surely cant be that intricate.
    I know you sent me wiring diagram but i cant see the source for activation of the lights and then the time out of such
    #20
  21. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Sorry i keep forgetting about this. Dont have the software on my laptop.

    From your haynes diagram it looks like that brown-white wire that goes to the central locking pump labelled Reading Lamp.

    I'll check tomorrow!
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  22. boost-addict
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    boost-addict Member

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    Dont worry aragon i forget stuff most days when im flat out at work.

    On that brown/white wite

    It reads 12v unlocked
    And reads 0.6v when unlocked....

    This is were im confused.
    I havent checked what it does if the lights are turnt on via the switch or the door opened
    #22
  23. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Its a switched earth.

    The 12v is appearing there THRU the bulb, because the other end is floating when the lights are off.
    #23
  24. boost-addict
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    No thats with the plug completly disconnected. Probing from chassis earth. When the 12v dropped theres no "earth" present across the meter to the chasis

    So whats the best way to hook up to that wire?
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  25. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Use it as your earth.

    Feed the lamps a fused live, probably safest to pickup the live thats feeding one of the existing interior lights. I cant make out the color code on haynes.

    And earth them to that brown/white wire.
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  26. boost-addict
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    Ok thanks ill give it a go. Ive actually got a little led strip sitting at work that i can use as a test light. The 12v feed yes. There is a permanent one present at the plug.

    Ill report my findings tomorrow. And as it seems my struggles with getting this info im going to make a how to for those who may wish to know or do the same

    So i presume (as ive never thought about it)
    Two 12v inputs will not damage a led light. Or is there a diode that can choke the 12v. But allow a earth when theres one present?
    #26
  27. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Its NOT two 12v inputs.

    Its an earth, which gets controlled by the central locking pump.

    Your measuring a voltage on it because the current is passing thru the bulbs (even if the connection your testing at is unplugged, theres still lots of other bulbs in the car sitting on the same wire!) and has nowhere to go becuase the brown-white is being disconnected by the CL pump when the lights are off.

    Think of it like an airline (circuit) with a buzzgun (interior lights) on the end.

    You put 100psi (12v) in one end, air flows down the pipe, thru the buzzgun and out its exhaust port (the earth). If you block up the exhaust port, and pull the trigger, you now have 100psi on both the input to the buzzgun, and between the buzzgun and the exhaust port. Because theres no exhaust path no air flows and the gun doesnt work, but measuring pressure inside the exhaust port would show 100psi. That doesnt meant the exhaust port is supplying 100psi, its just coming in the other side and has nowhere to go.
    #27
  28. boost-addict
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    boost-addict Member

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    Ah i see. Ok so will i need a pn diode?
    #28
  29. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    No, you wont need anything, it'll just work like a normal circuit!

    Connect + on your test lamp to the 12v supply (red grey i think?), and connect the - to the brown white.
    #29
  30. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    but it will feed back when the lights are manually turned on at the switches, that's what thee OP was hoping to avoid.

    I suggested he'd have to avoid it feeding back by using a diode?
    #30
  31. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    If the main lights are turned on at the switch then the switch pulls that wire to ground in the same way the CLPump would. A diode wouldnt help as the current flow is the same direction.

    It would only happen if you switched the main interior lighting switch on though. Map lights etc wouldnt affect it.
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  32. boost-addict
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    ok just to clear things up....

    i ran a test light using the earth from the brown/white wire and live from the red/yellow wire. unlock the car the light comes on, and locking the car turns it off, or times out

    turn the main light on or the two reading lights, the test light does not illuminate. (hurrah!!)
    open the door(s) the test light comes on and then times out when the door is closed or the ignition is put in.
    in short the test light is behaving the way the lights do normaly when the main switch rocker is in the middle,

    i can live with the out side lights coming on when i open the door, its not that bad to be honest

    so then i hooked the live up to the battery live input at the fuse box, and it behaved the same. which is good knowing i dont need a postive from the same cuircut,

    one thing i do what to do is put a relay in as in addition to the door handle lights. i may put additional lights in the front and rear light units, like the new cars have the "follow me home" feature, but, i would love to have them wired directly to the standard lights back and front, but can i use the source of power switched from the cl unit, to power the headlights and tail lights, or will this affect the circuit already in place, the power for the doors and any other light i hook up will be feed from the relay and not from the cl circuit.

    so what i need to do next is find were this brown and white wire goes, (i have the carpet out atm due to water getting in)
    which is why i want to get this done now so i can route wires easily.

    is one of the plugs by the footwell have the wire running via that?
    #32
  33. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    trying to power up the main headlamps starts to get into a real rats nest tbh.

    Sure, its doable, but its going to require a lot more than just jamming in a relay due to the way the existing bulbs are all powered thru a load sensing module for the bulb out monitoring, and the lights themselves are powered by the X contact relay which is disengaged with the ignition off. Sidelights might be easier.

    And yes, you can most likely trigger a relay using the feed you've found. Just put its coil across the brown-white and red yellow you've found.

    They will almost certainly be available at the kickplates in the front of the car. Will need to look up the diagrams to figure out where though.
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  34. boost-addict
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    Ok great. Maybe i should just (if i can be bothered!) install additional leds side light

    Well as the carpet is out im going to run wire for the lives in the doors as i can just earth out locally.
    Im not set on the idea of follow me home lights. Just thought it was a nice touch. Maybe even if its in the front fogs. Just like how my dads car does it!!
    #34

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