Guys i have a 06 vnl780 with a cummins isx and the tachometer has not worked since i bought it. Where does the tach read the rpms from so i can try and track down the problem (sensors, etc) Ive read some people needed to clean connectors to the ecu.. I dont even know where the ecu is located on this thing. If I find out my dash cluster is bad, is it possible to buy an aftermarket tach and just mount it on the dash?
***update***
I ran a test of gauges and all gauges move/work except tach