[T3] LEDs for directionals

Max Welton max.welton.2k at gmail.com
Thu May 19 09:11:16 PDT 2022

Interesting description Jim. Thanks.

The first relay came from my old 68 but whether it was original to that car
I don't know.


The new one came from West Coast Metric and looks very much like the one I


Superbrightleds do offer this resistor kit for those experiencing the
behaviors you described.



On Thu, May 19, 2022 at 9:24 AM Jim Adney <jadney at vwtype3.org> wrote:

> On 19 May 2022 at 6:48, Max Welton wrote:
> > So I got my turn signals working. I had to replace the 9-pin relay.
> >
> > And then, because I was curious ...
> >
> > https://youtu.be/lO9mmtTSz-M
> Tungsten bulbs have the interesting "feature" that they draw an initial
> inrush
> current that's about 10x their steady state running current. This inrush
> current is hard on those bulbs and explains why Tungsted bulbs almost
> always burn out with a flast at turnon. VW and their relay suppliers used
> this
> inrush feature to sense a burned out bulb. The TS relay expects two 10x
> inrush currents at turnon and if it doesn't get that, the flash rate
> doubles, as
> a signal that something's wrong.
> LEDs don't have any turnon inrush and they draw much less current, so they
> will tend to make the relay flash faster all the time, if that relay has
> the failed
> bulb sense feature.
> I don't know when VW started doing this, but I'm pretty sure '68 got it.
> Your
> car is a '67, which uses a completely different TS relay ($$$!) and that
> TS
> relay may not have the burned out bulb feature. (I don't know.) If you
> have a
> '67 owner's manual, it might tell you.
> If you had one Tungsten bulb in front and an LED in back, it's possible
> that a
> single Tungsten bulb might be enough to fool the TS relay, if the relay
> was a
> bit off spec or the front bulb was larger than stock.
> For anyone out there with a bad TS relay, I can sometimes fix them if it
> is
> any of the styles that's in a rectangular plastic box. I can't do anything
> for the
> earlier style that's in a large cylindrical metal can. The metal can
> flasher
> relays do not have the burned out bulb sense feature. LEDs probably won't
> work with them either, because they don't draw enough current to activate
> the flasher mechanism.
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
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