SIM, eSIM, and other ways to connect Tesla to the internet

Essentially, connecting an electric car to the global network occurs similarly to most other mobile devices. There are two options:
● Cellular connectivity;● Wi-Fi.

It's clear that the second type is only feasible either in a garage or by using another mobile device operating as a hotspot, which, to say the least, is not very convenient. Therefore, the primary method is connecting to the internet through cellular networks. For this purpose, Tesla cars are equipped with LTE modems installed on the MCU board. Most of them are equipped with eSIMs with numbers and codes of the countries where Tesla is initially implemented. 
The exception is vehicles operating on the Tegra processor (this includes Model S and X models produced before 2018), where slots for regular SIM cards are pre-installed, thus avoiding such issues. 
If an electric vehicle is purchased on the secondary market and ends up in another country, new buyers may encounter problems with internet connectivity. These may include:● Incompatibility of LTE modems with transmitting station frequencies;● Low communication standards;● Passwords;● Old accounts;● Roaming.
Obviously, the main solution to the problem should be considered as installing a new SIM card. However, very often the slot for a physical SIM card either does not exist or has a lower priority than the eSIM slot. "Handy craftsmen" have learned to solve this problem by soldering out the slot from the modem board and soldering a SIM card in its place according to the pinout.
This method can hardly be called successful. Firstly, the car owner again receives a stationary option, which will be difficult to change if the provider becomes unsatisfactory for any reason (unattractive tariff, change of location, etc.). Secondly, soldering the slot, located in the very center of the board, is, without exaggeration, a complex and intricate task; in case of an error, there is a high probability of needing to replace the modem, which costs between $100 and $300 depending on the model.

How to switch from eSim to SIM using LOKI

A much simpler, more attractive, and safer method looks like the hardware method of replacing the card using the diagnostic scanner LOKI. In short, all you need to do is connect the device to the car, go to the Online functions menu, and enter the necessary command, thereby changing the priority from the internal card to the external slot and activating it. All that's left is to insert the new SIM card into the slot. Please note that a full-size card is required, not a micro or nano one.

Sometimes, this slot—the place where you can insert the new card—is missing. In that case, you will need to install it yourself, as space for it is provided in any case. This job is much easier than soldering the eSim slot described above because the external SIM card slot has wide contacts and does not require specialized soldering or extra-class qualifications from the person performing the work.

Connecting the LOKI device to the car

So, we've figured out how Tesla connects to the internet. Now let's briefly discuss how our diagnostic scanner LOKI can be connected to the car's computer to perform necessary operations—not only SIM card replacement, but also any other among the multitude of tasks available to this unique equipment.

There are four connection interfaces:1. CAN. Connection via the CAN bus is used when working with all Tesla models. Through it, LOKI interacts with BMS, DI, TAS, CHG blocks, and others, enabling calibrations, data reading and analysis, removal of Crash events, and many other useful actions. The connection methods vary for different Tesla models.For Model S and Model X up to 2016, the LC001-CS cable is used, and after 2016, the LC003-CX. The situation is more complex with Model 3/Y, where there are no additional diagnostic connectors for the CAN interface. Connection to the bus is possible in the X935 connector using the LC003-CX cable and a set of pins, or in the X052 connector in cars after 2020 with Intel and AMD processors.
2. LAN. This interface is used for configuration changes, update work, activation of service modes, and other actions performed through the MCU. For this connection in Model S/X, the LC002-LS cable is used, and in Model 3/Y, the Ethernet-Ethernet cable is used. Additionally, they work with the replacement of the MCU2 configuration using a jumper in S/X models.
3. Base100-T1 (BroadR-Reach). This interface is a two-wire analog of LAN and is mainly used for LOKI's work with MCU Model 3/Y. Connection is made using the LC004-L3 cable for MCU with AP2.5/3.0, or LC007-LY (or repinned LC004-L3) for MCU with AP3.1 and 1000base-T1 port.
4. Base1000-T1 (so-called "turquoise connector"). A high-speed interface primarily installed in premium versions like Palladium and Plaid, rarely found in other trim levels. It operates on a gigabit protocol (hence another name— "gigabit"), so for connection to it, LOKI requires an additional interface converter (media converter).
These are briefly the connection options of our device to the car. In the next article, we will consider in more detail the connection of LOKI to each specific model, its features, and recommendations.