switch LEDs replaced, still NG

[munrof at sympatico.ca]

Hi Kent;

Hmmm, something isn't clicking here. I'm looking at your sig '89 200tq. What you are describing doesn't sound like the fog light switches I've seen from the 200 series. I've got one kicking around in the basement that I was converting to a headlight washer cut-out for the UrS4. It doesn't have a PC board, just a set of mechanical contacts and three light bulbs, one illuminates the switch and two illuminate the green triangle that tells you the fog lights are on. The bulbs are removable from the front of the switch. The back section of the switch contains the male spade connectors and the switch internals and pops out of the casing.
If your switch contains a printed circuit board, it's not what I was envisioning. What you describe indeed sound like LEDs, but AFAIK Audi didn't use LEDs for illumination until the last few years or so.
Sorry for the misinformation. Just what are you working on?

Fred
>
> From: Kent McLean <kentmclean at mindspring.com>
> Date: 2001/11/15 Thu PM 04:45:38 EST
> To: <munrof at sympatico.ca>,quattro at audifans.com
> Subject: Re: switch LEDs replaced, still NG
>
> Fred Munro wrote:
> >If that is an original switch, those are light bulbs (mit filaments), not
> >LEDs.
>
> When I apply juice to the leads, they are polarity
> sensitive. That is, I put the + voltage to one side
> (and - to the other), they light. Put the + voltage
> to the other side, they don't light. So I assume it's
> and LED (or there is a diode also buried in that tiny
> bulb).
>
>
> >On the fog light switch, the lower bulbs only light when the switch is in
> >the "ON" position, otherwise the bulb circuit is open.
>
> Yup. Switch is depressed (on) when the lights should
> light but don't. I have the original bulbs that work
> if I need to put them back. But I'm not getting juice,
> so I figure that's the problem.
>
>
> >The red switch illumination bulb is always on.
>
> I think the red is on only with the headlights.
>
> >Did you try pushing the switch "ON" to see if the lower bulbs lit?
>
> Yes. On, Off, it doesn't matter.
>
> >The other problem with these switches is that the contacts are lubed with
> >some green goop at the factory. This gets hard with age and insulates the
> >contacts. You have to open the switch and clean it off the get the
> >contacts working again - this includes the contacts for the lower set of bulbs.
>
> Since the switch is toast, I have nothing to loose
> by opening it up. But how?
>
> There are little white tabs on either side of the
> switch housing. But I pressed hard and they didn't
> budge.
>
> There are some vertical tabs on the PC board that
> look like they locate the PC boardd to the switch.
> Do you need to unsolder them to release the PC
> board?
>
> I managed to mangle the side of the casing in my
> effort. Now that I have a hole in the side, can I
> just spray contact cleaner through the hole?
>
> Thanks,
> Kent McLean
> '89 200 TQ, "Bad Puppy"
>
>