This am my tach needle went to zero while driving. All other gauges and speedometer function as normal. I plugged in the OBDII Bluetooth adapter and the PCM is sending the tach pulse signal and picked up by the Torque App. Since all the other gauges are operational I think that does rule out a ground issue. Is there anything else I should be looking at?

 

Try to clean the connector to the cluster and see if that helps...If not you're going in deeper...Could possibly be an interuption in the wiring to the tach...Or the tach just gave it up....

 

So I followed the diagnostic tests in the FSM.. Grounds good, continuity good...signal coming from PCM ....replaced the tachometer as apparently the magnets that drive it went bad. Tachometer, gauges and lights all are in working order.