Transmission failsafe program on 2nd gear.

[Nasov]

Transmission failsafe prog come on when I want to use 2nd gear. If I drive in manual mode and start from third and then drive on 4th and 5th no problem. If I want to use first is ok, but it takes more rpm /easy on the throttle / to go on 2nd in D mode, or just jump over 2nd ot put 3rd on, but in the 2 scenario the message Transmission failsafe prog comes on. There was a knock at stop and go before, but now is gone. I was sure it was a play in the back diff, but now when is gone, I think it cant be. Do not know if I succeed to explain the problem, my English is not very good, but I have to go 2000 km to go home soon and I have very little time to realize what is happening and decide whether I can fix it here / will actually cost x2 or x3 prices/. Actually I made about 300 kilometers trip in the weekend, 100 of them constantly stopping and turning off the engine until I discovered that I can drive only from third gear and over top without having failsafe program to kick in. Gear oil was changed before 3000 kilometers together with filter and gasket. The kicking in the transmission was there and before. Now that tap disappeared, transmission works very smooth and nice, but does not change to second gear. In manual mode jump from first to third straight and therefore immediately follows transmission failsafe prog. This message does not help me for browsing the net , the cause may have been the most varied and the results are too. I have new accumulator 100Ah. If anyone can share experiences, ideas ... Otherwise I know BMW diagnostics service which, for me to accept is associated with at least 1-2 weeks waiting and 110 euros just for review. Actually I wonder especially if I take the chance to get on so long trip, the third gear goes great and move normally, but I'm afraid if something may go wrong along the way and left as without a car, I have 2 1/2 years old kid ... On the other hand I have no idea what is happening and how to fix it and going in workshop like that proof to be bad idea every time. Maybe I can change the oil in the back diff and transfer case just to be sure?

Thanks in advance!