Here is a link to a thread on CF--

06 tach issues - Page 3 - Dodge Cummins Diesel Forum

And here is a short PDF that has pics of the screws that need to removed and of what IC's to "reflow" on the back of the cluster.

http://www.keepandshare.com/doc/3998...eg?da=y&dnad=y

Please know that I have not needed to do this repair on my 2005 (knock wood), but if I ever do have an issue, it is what I am going to do. Basic mechanical, and more importantly decent soldering skills, are necessary, but it is a relatively easy fix, and certainly the cheapest fix, for the tach problems that you guys are having.

 

Same problem intermittently on my 04.5

 

I have an 06 with same crazy tach issues. Pulled my cluster out and just hit all the leads with a solder iron on those ic's. Tach has worked perfect ever since. Ive done countless hours of forum searching on this issue. This was by far the easiest fix. And it was free, and only takes an hour or so maybe. After all my research I would imagine this would fix 90% or more of all these tach issues.

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Also do not over tighten the little screws that hold it all together, the board might warp slightly. That other forum suggested shimming the right side to keep it flat. But I just very lightly tighten the screws back. Worked for me.

 

I can repair this issue, it is in the cluster please email me for more information teg.travisbarnes@gmail.com