Re: 2008 Jeep Cherokee U0101 Loss of Communication with Transmission PLEASE HELP
Welcome to the garage.
If your jeep as the 3.7 L engine, then it has a transmission relay on the junction block. If your jeep is the 4.7L or 5.7L, then it has a transmission control relay in the PDC under the hood.
I would first inspect all wire bundles in the engine bay for shaving and clean the PCM/TCM connectors. Any wire break or bad contact in a connector due to moisture/corrosion, could give this problem.