ECU, like if its a NA chipped with a TT tune chip. It will not work. The TT and NA ECU are different in order to run the 3 speed fuel pump TT controller and the 2 speed TT AC condenser fan.
This was verified by DVD BURN (Gary) our resident electronics expert.
You probably tapped into another circuit... thinking it was the same... Can you just cut the wire in an easy place to verify if the AC and fuel gauge return to work properly. I hope you did not burn a circuit in the ECU... lol.. Good luck