Got a problem with a 1995 318TI Auto Transmission. It has the M42 Engine and A4S-310R Transmission. I have talked to several people including BMW. There are many opinions, Transmission Control Module, solenoids in the transmission, Shifter Cable/Selector Lever at transmission, Shift Interlock/Neutral Safety Switch Assembly.

Please excuse the long explaination but I am trying to show the details I have noticed.  Any help and suggestions would be appreciated.

I pulled the engine and transmission to replace the enginThe filter screen and shaft seals in the transmission were replaced. The Torque Converter was installed properly and filled halfway with new fluid prior to placing in bell housing. The transmmission is full of new fluid because the car is level and fluid does flow out while filling.

The car was driven after the rebuild and the transmission operated properly for a 30 minute testdrive.  After the test drive ,the car was parked and driven later that day for 5-10 minutes before I tried shifting to reverse but it would would not shift to any gear and seemed to be stuck in Neutral.  I added a little more fluid ( less than a quart) and the transmission seemed to work again but only for a few minutes.

When the car is first cranked, it may shift gear and operate as designed. After a short time if stopped and shifted out of the gear it will not shift back into gear. It appears to be Neutral and will not shift to other gears even though the shifter and Selector Lever are moving correctly.  I even disconnected the cable and moved the selector lever by hand.    

I also discovered that if put in DRIVE the transmission operates for 10-15 minutes then the wheels stop. I do not know if it slips out of gear and drops into NEUTRAL or whether the Torque Converter is still turning. The transmission did not make a noise. The increase in engine RPMs was the only indication something occurred.  I discovered if I kept the engine running and put more fluid in after the wheels stopped that the wheel started rotating but would stop in a few minutes.  The fluid I added would flow out if the plug is removed.  

I know the proper method to add fluid. The front pan does gets warmer but the rear pan remains cool. Since the transmission cannot be shifted in any gear after a few minutes and seems to be in Neutral, I do not know if it is getting warm enough or if the fliud pump or valves allowing a proper filling.

One suspect problem is the shifter, which is why I disconnected the cable.  I noticed when in Park the rear wheels rotated but could be stopped easily by hand.  This made me think it was actually in Neutral.  When shifted into Park directly by the Selector Lever this does not occur.  The transmission problem above still occurred with the shihter being disconnected.  The shifter problem is a  secondary issue but I suspect it is not my main problem. 

NOTE: I went to Pull-A-Part and got two Shift Interlock Switch Assemblies: one off a 1992 E3so6 and the other a 1997 E36 but I have not had time to install. 

The last possible suspect is the Transmission Control Module.  Since the transmission did work for a while and continues for work in a limited fashion, I doubt this is the problem.  My limited knowledge and experience with automatic transmission leave me open minded on this opinion.  The ODBI diagnostics limit the car from helping one diagnose its problems especially with transmission issues.    

Again: Any help and suggestions would be appreciated and sorry about the length plus any grammar, puncuation and spelling errors.