dimitrov

Hi guys,
I'm facing the strangest problem ever...
A month ago my transmission went down and I had to rebuild it completely.
The fault was the common one - broken planetary mechanism so all the internal mechanical parts were replaced with new OEM. Now I have the following issue:
When the transmission is cold until it reaches 102 degrees Celsius it works like a charm.
When it reaches exactly 100 - 102 degrees i.e. the normal working temperature,
it won't shift from 2-nd to 3-rd gear and returns to 1-st instead...with very high revs of course.
No CEL whatsoever, and the transmission ECU says that it's on 3-rd (I have onscreen software that displays the current gear position).
As the rebuild is under warranty they took the car back to the shop for two weeks and ran all kinds of test. For this tests they measure the oil pressure, replaced the whole hydraulic block with new, computer commands etc. everything was fine and yet the problem was there.
Now the pull the trans out of the vehicle again and they are looking carefully every single part inside all seems OK again.
Any thoughts and comments would be appreciated.

salimshah

Without giving it too much thought ,,, I think the problem is electrical in nature .. some solenoid is getting activated when it should not. We know when the temperature is low, the OD is disabled. I would ask they check wiring from each solenoid.

Thankfully I have not had transmission problem, but reading over the net, people talk about re-flashing the transmission by the dealer after transmission overhaul. If that was done, may be some thing went wrong in the process and you may need to re-flash again.

Salim

dimitrov

Thanks for the quick replay. Just two comments...
The solenoid part was also my first thought, but as I said they replaced (just for test) all the "brain" block (the hydraulic part with the solenoids) with brand new one and the problem persists.
Also the problem is shifting from 2-nd to 3-rd (not the OD) and only at temperatures of the fluid above 100 degrees Celsius. That's in my case after driving 50 or more minutes in high city traffic during summer time...Till it reaches these degrees works absolutely fine.
The part about re-flashing is interesting one. But how we explain the fine work for about an hour or so. If it was software the problem should be there at all temperatures.
The only logical explanation that's left for me is the existence of some foreign element remained after the rebuild, that was affecting the normal operation, when the pressure lowers because of the increased temperature...Maybe it's stupid one, but I don't know what to think anymore.