this is a strange issue but here it is.changed alternator and battery on a 1999 blazer.when I first started it up speedo went to a hundred and stayed there. turned it off restarted and now it stays @ 0 .worked fine before the change..any ideas?

 

Did you have it running with either the alternator not plugged in or connected to the battery or with the battery disconnected?

 

no but i drove it for a while and it started to work.. so thanks for the reply