I have a 06 Dodge ram 3500, auto, the tachometer is not reading correctly, at 55mph its at like 500 rpm, at 80 it shows 3500 rpms, it is not running at these rpms it just shows that. Where do I look? it has a TST R49 on it also.
Any suggestions?

 

I would check all the connections to you r49 first.

 

There was a thread on here last week (I think). General concensus was that lots of 06's (mine included) have been diagnosed with bad instument clusters.

 

If it is not popping any crank or cam codes I think it is a faulty tach. My truck has a erratic tach at idle even though the engine isn't idling any different.