Alfa Romeo 159 TEG reader

[riprex]

Hi guys. I?ve got an Alfa Romeo 159 2.4 diesel with EDC16C39. There is a bit problem with its TEG system - remote control key fob (PCF7941). When it?s too hot or too cold weather, remote control is not working until I unlock car with mechanical key and after few hours whole situation repeats. The problem is somewhere in TEG key reader slot in dashboard - it is proved by many other cars, where it was solved by replacing slot unit. It contains main processor NEC 78F0818, eeprom 24LC04B and some other stuff like a CAN transmitter, stepper motor driver, remote control reciever etc. New unit from dealer is around 800 euros which exceeds whole car value, if this Alfa has such a thing, so I decided to change unit from scrapyard car. But immediately there was a problem - there are key transponder data in the eeprom, so I swapped eeprom from original unit to the one from scrap yard, but that did not work at all - car says security not available and electronic key not recognized, so I decided to swap whole processor, but that did not work either. When i placed them back to original unit, car works like before, but cold/hot weather issue persist. Do you have any idea please, how to replace this unit or how to fix it to work properly? Thank you very much for anything helpful.

[riprex]

Well nobody any suggestions? I am running out of ideas...

[simaservis1108]

I have struggled for months,since my friends drives a Fiat Croma...
Only TEG with updated part number doesn't have that problem.
I think it has something to do with temperature sensor reading,like when it is cold it won't unlock,you must first unlock it on key,then remote works....

[riprex]

Thank you for reply. I think, that old TEG reader has bad capacitor which change its capacity due to temperature changes and that is reason of malfunction. I have TEG from scrapyard car with new hardware revision. These should not be affected with this problem. But adding new TEG reader to the system is my problem. Repairing old one would be difficult if no impossible. I have tried to first flash eeprom in new unit with data from old (contains transponder data) but that did not work so I swapped CPU from old unit to new and that also failed. Soldering was good and CPU putted back to original unit works as before. So my problem is what I need to do to swap TEG unit from another car or how to virginize TEG unit, to add it with Fiat Examiner like it was completely new unit.
TEG unit contains these IOs:
TDA 5200 - ASK single conversion receiver TLE 4207 - Dual half-bridge driver TJA 1054AT - CAN transciever LM 2901 - Quad comparators BAT 160A - Schotkey diode PCF 7991AT - Transponder basestation NEC 78F0818A - 8 bit microcontroller 24LC04B - I2C 4K eeprom

In my mind only CPU and eeprom could contain some data, so if I have another TEG, swap CPU and eeprom it should work, at least with same problems with remote. But it is completely dead and could not recognize the key.

[lirinikut]

you must change pcf7991AT AND 24LC04B AND ALL WILL BE FINE

[duzaven]

Hi,
Maybe you still have the dump from eeprom 24LC04B. At my TEG dump from 24lc04 damaged.I have Fiat Croma, but I think the difference is not big
Thanks for help