Crank angle sensor issue?

[undefined0000]

What feeds the ECU the engine speed?

Basically after I drive the car for a while and if I've idled for a little too (full operating temp)

If I turn the car off, then turn it back to just "ON", the Tach shoots to 4, mind you the engine isn't running. What could be causing this? Not sure if its causing any operating issues, I don't really have HUGE issues driving around town.

 

[undefined0000]

Nopes

 

[BogusSVO]

My best guess, would be a gauge cluster ground and/or dash ground.

 

[undefined0000]

Sounds like a good enough theory. So a warmed up CAS wouldn't show symptoms like this before it croaks?