I have an 05 Ram 2500 5.9L Diesel, with 233,000 + miles. I rebuilt the tranny at 200,000 miles and it has been doing fine. I'm moving from CO to TX and hauling some heavy loads but no where near capacity. I was going over Ratong pass and the tranny shifted to a lower gear to get me thru the last couple of miles of ascent and the check engine light came on. I pulled over, hooked up my scanner and I'm getting the P1751 and P1753 code. This tells me the Tranny Throttle Valve Actuator (TTVA) is not reading the valve position properly. I have to get to around 2400 rpm to get it to shift from 1 to 2. I ordered a new TTVA, put it on, and same problem. Sent it back (Ebay) ande ordered one from Amazon. Put it on and same result. So I'm on my second TTVA still have the codes and delayed shifting. Still have lots to haul and don't want to damage tranny pulling loads with this delayed shifting. I did put the tranny in 2nd and it could tried to shift (hard shift) but couldn't shift. As for testing the other two TTVA's, I disconnected them from tranny, left them connected, turned on key and no movement of TTVA to find "0". I jumped pin slot 1 and 2 on connector and it threw a P1749 code. Remove the jumper and the code goes away. My scanner will not clear the 2 original codes and I disconnected the battery for more than 30 mins and turned on key for more than 30 secondst trying to clear memory. But still getting the two codes and delayed shifting. Ialso delayed starting engine for more than 30 seconds (key in run mode) when I installed each of the 2 replacement TTVA's for zeroing. Before I return a second one does anyone have anyother recommendations of what I should be checking or doing to see if something else is causing this? Any help would be greatly appreciated. Thanks in advance.