trip computer wierdness

[Beer, Jerald S.]

If the speedo is dropping, the computer is not picking up the speed, it
reads "0" and the mileage goes down. Probably a bad solder joint, if you
look in the FAQ, there was a writeup and pic of where the bad solder
joint typically is. An old test was to pound the top of the dash above
the speedo: if that helped, definitely a bad solder joint. Instrument
cluster needs to come out for repair. Not too hard, just go slow and be
careful. 
Regards, 
Jerry 
200q20v