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LED Trailer Light Issue?

Discussion in 'T3 & T4 Tech Help Clinic' started by GypsyWannabe, Feb 21, 2011.

  1. GypsyWannabe

    GypsyWannabe Active Member

    Quakers Hill, Sydney
    I had to buy a new boat trailer today, as the old one fell apart. :wtf: So, I picked up a nifty new trailer with submersible LED lights. When we tested it on the T4, they didn't work. Hooked up to the battery tester thingy, the trailer lights worked. The T4 has a 7 pin round plug and I have an adaptor to convert to the 7 pin flat plug on the trailer. The adaptor tested OK, too.

    The trailer guy said some of the newer European cars need a transformer for LED lights - try VW. So I go to the spare parts section at a VW dealer down the road and he says I won;t need that for a '94 T4. It's only needed for the newer VWs with LED lights and computers - you have to program them in (or something like that).

    The adaptor looks a little old, so I bought a new one at Supercheap on the way home - this one has little LED test lights on it - they don't light up either. The old trailer lights (non-LED) work fine.

    I rang my auto-electrician to see if he's heard of anything like this - he hasn't - but he will look at it tomorrow for me.

    However, has anyone else experienced this problem? Any ideas?

    If it is a problem, the trailer guy will swap over to normal "old-fashioned" lights for me but if I can sort it out that would be better, as LEDs seem to be the bee's knees.

    Appreciate your help, in advance.


  2. I was just browsing around the net for a LED Third brake light & read that LED's dont draw enough current to allow the flasher unit to function. There is something that you can buy that goes intothe circuit that draws extra current apparently. Not sure if this would be your issue or not. It's just what I have read.

  3. grumble

    grumble Well-Known Member

    That is right Brenden,there is a unit available to put the resistance into the circuit,one of my customers made one himself with a small globe in each circuit to put resistance into it.The commercial unit is made by Narva I think and should be available from Dealerships that fit tow bars or the auto electricians.
  4. jon ward

    jon ward Active Member

    Travelling Australia
    Kinda defeats the purpose of having LED's though doesn't it?
  5. Grantus

    Grantus Well-Known Member

    Southern ACT
    I've replaced a few of my bulbs with LED's, added a few extra, including an eye level brake light.

    The indicators will flash annoying fast with LED's on a standard flasher unit.

    I bought and installed an LED flasher unit, which slows the flashing rate back to the speed the standard one works at.

    LED's will only work if wired one way, the positive terminal on the LED is connected to the + wire from the battery. Unlike filament auto bulbs, that will actually work on either side.

    Don't know if any of this helps....:rolleyes:
  6. t4camper

    t4camper Active Member

    rainy Maleny
    There is nothing fancy about the '94 T4 lights.
    The small load of LED trailer lights will not change the flasher speed as the standard van lights are still there. If you change the van lights to LED globes then the flasher speed will be fast. Same occurs when you blow a globe on the van. Fast flasher indicates blown globe.:)

    I would look at the earth return wire connection either on the new trailer or on the van.
    Low power consumption of LED lights may have insufficent energy to overcome a high resistance [bad] connection. More likely if none of the trailer lights work at all.

    The old bulb draw more current and so have more punch to get past a bad connection although they will have voltage drop across that bad connection. Also bulbs will allow back feeds to the return to the chassis earth with a bad connection. Classic sign is some lights work, but then when brakes and flasher are on together, brake lights go out when flasher should go on. :eek:
  7. GypsyWannabe

    GypsyWannabe Active Member

    Quakers Hill, Sydney
    Thanks all. I suspect a short at the connection on the van. The lights on the box trailer worked fine the other day but I tried the old boat trailer lights again and with the taillights on and the indicators at the same time, the tail lights would flash, so there is power getting through but not correctly and maybe the LEDs don't have the power to punch through, as you say.

    My sparky should sort it out tomorrow when I tell him the symptoms. I might as well get him to wire it to a modern 7-pin flat plug anyway, rather than use adaptors.



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