Anyone know if Transmission control module effects tachometer. Looked at wire diagram and don't see and connection for it. For years I had issues with tach reading 0 rpms while idling and works when I drive. I replaced tcm today and it idles normal now at 800 rpm's. Just curious

 

on the newer Rams I know the PCM controls the tach but you can download the Service Manual from the link in my sig and check it out. There is a copy for the 02 in there

 

I looked at it but it doesn't show any wire for it.

 

I looked at it but it doesn't show any wire for it.