Transmission not locking up into overdrive

I have a 2001 Montana. About a month ago the transmission would not look up into over drive. The transmission works greatly otherwise. Two week prior I change the air filter, while do so, I unhooked the two sensor in the hose from the filter to the throttle body and the plastic pipe to remove the hose to change the filter. I check the plastic pipe and the other end, back of the engine, is not connected to anything. What the purpose of the pipe and could this affect the transmission not going into overdrive? What should it be connected to on the back side of the engine?

I have a 2001 Montana. About a month ago the transmission would not look up into over drive. The transmission works greatly otherwise. Two week prior I change the air filter, while do so, I unhooked the two sensor in the hose from the filter to the throttle body and the plastic pipe to remove the hose to change the filter. I check the plastic pipe and the other end, back of the engine, is not connected to anything. What the purpose of the pipe and could this affect the transmission not going into overdrive? What should it be connected to on the back side of the engine?

Answer:
My transmission did the same thing, no overdrive, the problem turned out to be the 4th clutch hub assembly. The teeth stripped off the spline (was told a common problem due to design) Had to get a 2300.00 rebuild.

The "pipe" attaches to a hole in the rear valve cover. It's located on the drivers side of the engine under the bracket the ignition modules are mounted on to. You should be able to squeeze it back in there without removing the bracket.

Answer:
My transmission did the same thing, no overdrive, the problem turned out to be the 4th clutch hub assembly. The teeth stripped off the spline (was told a common problem due to design) Had to get a 2300.00 rebuild.

thank you. knowns what goes on since no codes are being displayed. a transmission shop suggested this might be the problems. thank you.