Instrument panel issues, 1995 90

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   I wanted to share the problems that I have been having over the last
year or so with the instrument panel. It is a 1995 90q, manual trans,
manual ventilation controls with 220,000 miles. 1) The speedometer would
not work early in a trip during cold weather, and would start working
after the car warmed up. The cruise would not work while speedometer was
acting up. 2) The clock would reset itself to 1:00. I could never catch
it in the act of re-setting, so I didn't know when it would do it. I was
eventually able to duplicate the problem by wiggling the clock set knob,
discovered by accident. 3) The back-light went out on the beloved
outside temperature display. 4) Intermittent general back-lighting. 5)
Finally, the ignition switch took a dump, sometimes leaving the starter
motor engaged, and dropping some accessories. Luckily I heard the
starter motor running, so no damage done. This is the third time this
has gone out on this car. Solutions: 1) Wiring diagram shows that cruise
control gets VSS (vehicle speed sensor) signal from the speedometer
circuit board. Upon dis-assembly, I found that there are multiple
modules in the instrument cluster. In the case of the speedometer, the
VSS signal come into the main cluster board via the wiring harness, and
is then fed to the speedo by pins and receptacles. This allows repeated
separation of the layers for initial assy and later maintenance. The
pins are tin plated copper and had corrosion on them in exact the point
the receptacle made contact with them. I needed a magnifier to see this.
I scraped the corrosion of and then cleaned them with contact cleaner.
The speedo problem has not recurred since this fix. 2) The clock is a
similar modular pin-fed device, but in this case, the pins had cracked
solder joints where they come through the clock circuit board. Since I
resoldered these, the clock has been working solidly. 3) The temperature
display is another module, and upon disassembly, I found a small light
bulb soldered in place. This was an easy fix. I don't think Audi intends
for this lamp to be replaced. Also, I do know that this one has been
covered here before. I like having the temperature display and am glad
to have it back. 4) Self explanatory, although the replacement lamps are
not super easy to find. Even the dealer parts dudes had to dig to find
the lamps. Weird. 5) Ignition switch. Replaced with new one from dealer.
New one was all black plastic, instead of a mix of black and white. They
changed the design from some old junk ones I have around. Main return
spring appears to be mounted in a better place. All the old and new
switches I have were made in Germany. While I had cluster out and apart
I was able to carefully clean the plastic lens, and get accumulated dust
off of the faces of the gauges. Dang instrument panel looks new. I
highly recommend this. Taking the instrument panel apart to its
individual pieces was not too bad. Very doable if you take your time and
have a nice clean and well lighted bench to lay it out on. Also while
apart, I was able to figure out that the little 'dummy' button next to
the fuel gauge is actually a calibration/zero adjustment. If you want to
adjust the full or empty position of your fuel tank needle, pull the cap
off of the nearly flush knob near the fuel gauge with a nesdle nose (it
mars it up a bit) then turn the inside of the remaining knob with a
metric Allen wrench. I would never have messed with mine because my
gauge was accurate, but I diddled with it trying to figure out what it
was, so now I am committed. I'll keep a gallon of gas on board until I
see if my 'E' is accurate.