No Overdrive

[Jeremiah Barrier]

Hello I am having trouble with my 2003 dodge 3500 crewcab 4x4 diesel, the 48re transmission won't engage torque converter lockup at about 50mph like it always has in the past, it just stays at 2000rpm at 50mph and 2500rpm at 60mph. It shifts fine up till 50mph but doesn't hit overdrive and lockup the converter (I figured it's overdrive and converter lockup because as soon as it hits 50mph it's like it shifts twice and the rpms drop to 1400-1500 rpms and crusies nicely). Recently my wife was driving it on the freeway it started hunting for gears and erratic shifting then she said it shifted extremely hard once and started losing speed up a hill, she got it home and I found a cooler line that got a hole rubbed in it and was really pumping out transmission fluid. I fixed that so no more leaks, dropped the pan and did a filter change and refilled with fluid and now it won't shift to overdrive. I thought it was shifting to overdrive but when I'm up to speed and push the overdrive off button and there is only a 100rpm rise in rpm and a couple seconds later it just drops the 100 rpm back down without hitting the button. So I'm not sure if it Hitting overdrive or not. I replaced the overdrive/clutch up lock solenoid and that did nothing. I replaced the governor and transducer solenoids a year ago with bd diesels upgrade kit but I don't know if low fluid will cause them to go out or not. I put a switch on to lock the torque converter up and that locks up. So I put a switch on the overdrive solenoid( 3-4 shift solenoid) but that didn't do anything. The only other weird thing is Throttle position sensor reads properly 0-100 on the scan tool when I'm in engine diagnostics but when I read the Throttle position sensor in transmission diagnostics it stays at 7.5%-7.8% with no Throttle input and only maxes out at 68% with the pedal on the floor. How can the engine read it right and the transmission read it so different. I need some help if anyone has any suggestions. At no point will the check engine light come on or flash either. Thank you

 

[cerberusiam]

If you put a mystery switch on the OD circuit sense wire and it did not lockup it is likely a mechanical issue. I would check OD pressure with the mystery switch engaged to see if it is getting any pressure, if you get a bump in pressure when you hit the switch but no engagement the OD brake clutch pack is gone or the OD clutch support is bad.