the tach in my truck doesn't work I just converted it from a cluster that didn't have one to one that does (it has the wire allready there for it) how can I check the tach itself?

 

what year truck.. on the 99? and newer with the digital odomoter, you can hold in the trip meter button while turning key to ON. continue holding in trip meter until it says CHEK, and then release. cluster will go through a self test and operate the gauges through a 3 step sweep of about 1/4, about 1/2, then full. this includes tach.

 

the truck is a 94