5K Starting Probs

["McMurray Michael" <McMurray_Michael@macmail1.cig.mot.com>]

Hi all:
I've been lurking the group for a couple of months now and, needless to say,
I'm impressed by the expertise and devotion to the Audi marque.

My particular problem is that my '87 5KCSTQ (147K mi)won't start when it's
warmed up.  The engine cranks fine, but the fuel pump won't spin and put out
any pressure.  I've replaced the pump relay and the pump, but to no avail. 
The code is "2112" which the Bentley says is "no signal from the ignition
timing sensor, improperly adjusted distributor."  It is the only  code stored
and is the same whether the car is startable or not.  I failed to check for
spark, but I did check the wiring for the sensor all the way to the MAC 11 and
the sensor ohms out okay (approx. 1k).  Once the engine is running, it goes
great!  Really strong, no bogging, pulls to redline.  The car is completely
stock, with the exception of driving lamps.  No head or timing belt work done
for at least 30K miles.

Also, what is the purpose of the multi-leaded temp switch underneath the
coolant hose at the front of the cyl head?  It's shown in the Bentley diagrams
but not in the schematics.

Any ideas? MTIA...
Michael McMurray