It won't shift into overdrive by itself, i can

The OD solenoid in the transmission or the transmission control module is defective. It's also possible the torque converter clutch plates are worn. That's where over drive comes from

OD clutches are gone, leaks at the valve body, Or bad seal for OD.

check your trans fuse. some vws have a fuse for od. otherwise could be the cable out of adjustment or a blown od cluch/ tork converter. check fuses and reset computer by un hooking battery for 60 seconds

look for knock sensor codes in the history on the engine computer

there inside the tranny you have to remove the pan to see them but thats not going to be your problem go buy a can of TRANSX first!! and try that if that helps then you need to plan on rebuilding your tranny or replacing it

have a 1998 K3500 silverado 4x4 with 454 motor and 4L80E transmission. I can not get over 55 or 60 mph. At that speed the transmission down shifts from 4th (OD) to 3rd. The speedometer also drifts from about 50 to 65. If I try to speed up it will down shift to 3rd. I have replaced the VSS on the trasfer case. Is there another speed sensor somewhere? Or could it be the TPS? The truck drives and shift normal up to this point. where should i look next. thanks

I have that exact same truck and transmission and My Transmission did the exact same thing about a year ago and there was some kind of snap ring inside the transmission that broke. I originally thought it had to be an electirical problem because the truck shifted fine until OD or if i turned OD off. The 4r70w is a light transmission and i would suggest you have a shift kit put in and they make a heavier kit to beef it up.. Sorry its probably not the new you were looking for.

the OD shift solenoid is malfunctioning or has failed. changing this will bring back the OD. the solenoid is located in the bottom of the transmission pan.

you may have damaged the overdrive gear, a local transmission shop would be your best bet. for good troubleshoting and estimate.