So yesterday I drove home a 2009 3500 dually with the G56 trans. I spoke to the salesman before I left and had them enable the high idle, however after we tried raising the rpm's it wouldn't work. We followed the directions in the manual but maybe missing something. Now searching the forms I see that I may need to ground out the number 22 pin to get this to work correctly. I also see that Geno's was supposed to have a wiring kit to do this, and I cannot locate it on their webpage. Any further help would be appreciated!

 

If it's the same as the late 5.9's with a manual trans then yes you need to ground the pin on the ECM although no kit needed. Do a search here for the part #. You can buy the pin with a pig tail wire for a few bucks from any Cummins shop.

 

Got it! Actually I did a ton of reading on this and other pages. Grounded a green wire under the dash, and it now works perfect.

 

That's great. I remember that now. The 5.9's don't have the "green wire". I was told that I could do that on my 5.9/G56 and after looking for the d@mn wire for a couple hrs I gave up and did the ECM pin.
That is a 6.7/G56 only method I believe.