HELP! Random warning lights on C70

I have a 1999 C70 convertible and when I crank it up i never know which
warning lights are going to come on. Sometimes it's none. Sometimes it's
ABS and the one warning about poor traction. Sometimes it's Check Engine
(and my OBDII reader says it's "Engine Speed" and I can clear it). Anyone
have an idea on what's causing this?

 

Not necessarily your problem, but easy enough to check... really weird
electrical problems make me think of the ground between engine and chassis.
A check of voltage between engine and body with the engine running is a good
clue - if there is only about 1/10th volt dc between them it's okay. If
there is like a volt the ground needs to be fixed.

Mike

 

I'm having the exact same problem with my 2000 C70. Furthermore the
speedometer will quit working for awhile then start again and the
cruise will not work. In addition the odometer looks like ------
(dashes) then comes back. Sometime turning on and off resets
lights/speedometer other times it doesn't. Driving me nuts! Does not
effect performance. I had the ETS updated with the latest just a month
ago which resolved my hesitation problems. help! Thanks!