Tach only moves while cranking

[MeanGreen]

On my 93, the tach will read about 300 rpm while cranking. Once the truck is running, the tach is dead. I even held the key in the "start" position after it started and it still dropped to 0. I did this thinking that power was getting cut to the guage in the run position. I also removed the sensor and clean it. No luck. I know the sensor can be checked, but it there anyway to check the tach itself?
Jerry

 

[Optikalillushun]

this is a common problem...im going to check the main ground at the guage cluster first and if that doesnt help im going to replace the sendor...since urs works and then doesnt id say the sendor is shot...mine is irratic.

 

[MeanGreen]

Thank you.

 

[Agnem]

I suspect a wiring or gauge cluster issue. Usually the tach sender works better at higher RPM than low, if it is faulty.