RE: Strange Speedometer Behavior

[Phil@sievers.com (Phil Payne)]

In message <9412301819.AA25316@us2rmc.zko.dec.com> Michael Moy 30-Dec-1994 1316 writes:
> This morning my '89 200TQ's speedometer started behaving strangely.  The
> needle sort of "bounced" between two readings like, for instance, 25 and 35
> when I was driving at an estimated 40+/-mph according to the tach.  The period
> of the bounce was about 1 second.  Increasing the speed decreased the magnitude
> of the bounce and also decreased the period.  (The bounces were smaller and 
> more frequent.)  During this period, which lasted for about 25 miles, the 
> cruise control would not operate. 
  
Very similar behaviour by my tachometer preceded the final demise of the inlet 
manifold -> chassis grounding wires.

If the instrument's one of the electronic variety, which I've seen in European 
cars with cruise controls, check the ground straps of the component the 
sensor's attached to.

Phil Payne
Sievers Consulting UK
Vice Chair, UK Computer Measurement Group
Phone    +44 385 302803
Fax/BBS  +44 1536 723021
Fido     2:2503/415
CIS      100012,1660