Re: '93 90 seat heater switch light (long)

[Chris Newbold <cnewbold@transarc.com>]

crossley family wrote:
> 
> Can anyone tell me the specs and a source for the seat heater switch
> light
> for a '93 90q?  I have taken the expired bulb out of the switch thinking
> it was a LED, but once out it looked more like a red mini incandescent

I recently BTDT on my '93 90. The bulb is indeed a tiny incandescent.
I didn't have any luck finding a suitable replacement; there are plenty
of suitable bulbs, but none of them are *red*.

All of the red ones that I found were far too big to fit (at least from
Radio Shack).

I think the switches on these newer cars are a little different than the
older ones... I got the impression that the older switches used a clear
bulb with a red filter, which made it easier to find a replacement...

> bulb what with its skinny round lead wires.  The voltage to the device
> varies from 0 to 0.25 volts depending on the potentiometer setting for
> the dash lights.

Hmm. That wasn't what I found. I checked the voltage across the two
leads
of the lamp, and it was a fixed 12v. That made sense to me, since the
seat-heater switch lamps are always on, and I don't remember them being
dimmable...

So, working from that, I tried a little reengineering: I replaced the
lamp with an LED, figuring that that would have a *much* longer life
than these little bulbs.

It was challenging, trying to get an LED and the needed resistor into
the
same space as the tiny bulb. At first, I tried to fit an ultra-bright
LED, but all of them were just too large in diameter to fit into the
hole.
In the end, I settled for a mini-LED and I was able to squeeze the
resistor
in underneath it.

It's not terribly bright, however. It manages to light the "smoking
seat"
icon fairly well (I generally keep the instrument lighting very low,
anyway)
but doesn't have the juice to light the numbers on the rotary dial.

If anyone wants more details of this experiment please let me know; I
can
post part numbers, resistor values, etc.

-Chris
1993 90CS 63k