1996 cummins shifting problems
 

I have 1996 12v 4x4 automatic transmission I just recently had new turbo injectors valve springs 3 piece manifold and transmission rebuilt. Since I got it back the transmission shifts 1-3 gear really fast it's in 3rd gear at 15 mph if you let it idle and pull it self not touching the fule it still shifts into third gear. I sent it back to the transmission guy he's went back into it checking everything and even changed the valve body and it still has the same problem no engine light or anything. I'm trying to figure out what would be causing this issue I'm new to the form just trying to get any help getting my truck straightened out. Thank you

Welcome to Dodge Ram transmissions. They shift early, and the less load there is, the earlier they shift. They want to be in a high gear, they don't waste any time getting there, and if you don't come to a complete stop or put it to the floor, they won't shift back down either. The best solution is to shift it manually and not give it the option.

The truck didn't have this problem until I had the truck built

It's possible that you're TV cable is out of adjustment, or your TPS sensor coincidentally started crapping out at this moment. Did you do a stock rebuild on the trans or is it upgraded? What you describe does not sound unusual at all. When does it shift if you're standing on it?

Did an upgrade transmission build to hold the new power. I already tried the tv cable adjustment and a new one nothing helped even the transmission guy went back into it to check everything he said it was the pcm but I don't think so and if you stop and hold it wide open still is in third gear at 15 mph

Well that does sound odd. I doubt the PCM has anything to do with it, the only thing it controls is OD. 1-3 are manual, and their shift points are manual and based on the throttle valve. I suspect something is amiss in the upgrade. How does it drive if you turn off OD and shift it manually?

If I shift it manually it does alright. If I turn the od off it makes no difference same issue I'm just trying to figure out what could cause the issue from doing the upgrades?

No idea. More power = less slippage required from the trans to accelerate, and modded trans generally = more line pressure, so there's less slippage. More power + more line pressure generally = shorter shifts as you don't need the same revs anymore to get the same amount of work done. That it would idle up to speed and be in 3rd at 15-20mph with a turned up motor and fortified trans isn't unusual at all. That all being said, the shift points should be much later under load, no way it should be in 3rd gear at 15mph at WOT. Whoever built your trans definitely has a mystery to solve.

That's exactly what I was thinking it made it a pain when I first got it back pulling a load from take off it would lug it out bad but once I got past that point it pulled like a champ. I sent it back and hes working trying to figure it out so hopefully when I get it back this time It will be good and I'll let you know what that did to fix it but right now still a mystery and trying to figure out the issue