The cable connects to the old analog radio connector to provide power to the new digital radio and also connects the digital radio to MCU2. It includes a blue LED in one connector to confirm radio power (somewhat unnecessary, but may be useful). The cable includes the 3D printed connector cover as well.
We use the exact same connectors that Tesla uses so no wire cuts are required. We also use aircraft wire that is designed for high temperatures with triple coverings (twisted pair, a braided shield, and an outer covering. In addition, we added a heavy-duty protective wrap for the cables coming from the radio.
As part of the project, you'll have to replace your analog radio with a new digital radio (not included). Part numbers and instructions are in the article. This is not a trivial task! We recommend getting the radio that matches your current car. For example, if you have AM/FM/XM, get the digital FM/XM radio. Note that Tesla does not make a digital radio with AM.
If you disconnect the analog radio when you still have MCU1, over-the-air software updates are disabled. Connecting back the analog radio restores the ability to get updates.
Tesla in the past has NOT been willing to provision the digital FM radio. Perhaps your tech when installing MCU2 will do this, but we have zero control over if they will or will not. If Tesla will not provision your car, the radio will not work, although there is no harm having it connected. Tesla corporate may relent if enough owners put pressure on Tesla.
We recommend installing your radio and cable prior to the MCU2 upgrade - and ask Tesla to connect the FM radio ethernet connection to the back of MCU2. The MCU2 connection is a trivial task when MCU2 is being installed.
We have a limited number of cables and we are not planning to make more when they sell out. I'm not trying to goad you into buying, but I'm honestly not making any money on these. They are time consuming to make and some parts are exceptionally hard to obtain.