Electrical schoolwork... part Deux

[Louis-Alain RICHARD]

Well, 24 hours later, I have an answer.

The red LEDs I bought today (generic high intensity variety, 3 for 1$, no
packaging nor specs sheet) works fine with a 820 ohm/1W resistance. 

In fact, with a supply of 13.5VDC, the LED voltage is exactly 1.7V and the
resistance is just warm to the touch.

When I tried with a 500 ohm-1/4W resistor, the LED was kinda bright and the
resistor was kinda hot... so durability was questionable.

Bad news though, as there is just no space in the switches to install a LED
+ a resistance, no matter how small it is. It would have look nice for sure,
but the actual bulb in the switch (W5 1.2 Watt 12V) is about the same
diameter as the LED and not much longer.  
So long for the LED mod, it is not feasible unless one can find a real 12V
LED that is very short in length.

But I managed to replace the burned bulbs with new ones with a little
creativity. 

Originally, the bulbs were soldered to their contacts in the switches: but
20 years of oxidation, grime, grease and all made soldering new bulbs just
impossible. So I tried to mechanically assure contact by drilling a very
small hole (where the old bulb was soldered) in which I pass the lengthened
bulb contact wire. Then, I wedge in the hole a small piece of wire and
Bingo! here is the light!

Result? All the switches are now lit, but not perfectly. 
I mean, one of them is very dim (maybe there is some dirt on the translucent
pictogram), it is the one for the seat heater.

And I found that the emergency flasher bulb is not always on (with ignition
on) like ALL the 4 other, but in fact it is connected to the circuit I can
adjust with the rheostat. Maybe the switch is from another car (80-83
Coupe?), or is specific to our market because it is the only one with a
DOT-approval number embossed in the plastic. Strange.

So my problem (...and what a difficult and important problem it was...TIC)
is now solved but my wanna-be-pioneering work was cut short by a space
constraint. I guess that many engineers are facing that exact same
problem...

Thanks all for your input, knowledge sharing and general interest, it was
fun indeed.

Louis-Alain
1983 urQuattro, with very old technology and staying that way!