Modification of the BMW GT1 diagnostic interface, EDIC for BMW computer diagnostics via Wi-Fi using DIS
The ability to use a wireless connection for BMW computer diagnostics via Wi-Fi appeared in the original MoDiC 3 diagnostic tool, when the diagnostic interface (orange head) was separated from the diagnostic computer (MoDiC 3 tablet). From this moment on, all further versions of DIS began to support wireless communication at the software level.
The orange diagnostic head and MoDiC 3 tablet, manufactured by Kontron, have PCMCIA Wi-Fi cards Netwave AirSurfer Wireless, standard EEE 802.11 2.4GHz. The SCO OpenServer operating system and the BMW DIS diagnostic software do not have universal software and hardware compatibility; therefore, wireless communication in DIS can only be activated between two identical AirSurfer Wi-Fi cards and only between the orange head and the MoDiC 3 tablet. Any attempts to connect the head via radio communications to another mod or computer are doomed to failure.
MoDiC 3 has been replaced by the BMW DISPlus and Group Tester One (GT1/MoDiC 4) diagnostic tools, and with them a new diagnostic interface — BMW EDIC (yellow head).
All three diagnostic devices have PCMCIA Wi-Fi cards Symbol Technology Spectrum24 LA3021, EEE 802.11 2.4GHz standard. As with MoDiC 3, wireless communication in DIS can only be activated between these three devices. All drivers and settings in DIS are strictly tied to specific components of the original diagnostic devices.
In theory, installing the same Wi-Fi card in an IBM T30 laptop and native DIS installation will enable radio communication between the laptop and the yellow head. But I haven’t seen any practical implementations.
There's nothing magical about the IBM Thinkpad T30. Some say that DIS works on the T30 because it has almost the same motherboard as the BMW Group Tester One. But that's absolutely not true.
IBM T30 — has a typical motherboard for IBM laptops of that time.
Group Tester One — has a dedicated industrial PC manufacturing motherboard from Fujitsu-Siemens.
DIS can be installed on any computer whose hardware is as similar as possible to the Group Tester One tablet, generation of processor, chipset and general hardware layout.
Conclusion — any attempts to use the standard radio communication function to connect the diagnostic head to DIS installed on a VMware virtual machine are doomed to failure. Without MoDiC 3, GT1 tablets and stationary DISPlus, you can forget about using the factory Wi-Fi connection.
But no big loss. EEE 802.11 — is the very first Wi-Fi standard, introduced in 1997. It has only 2 data transfer rates of 1 and 2 Mb/s, as well as a complete lack of backward compatibility with subsequent 802.11a/b/g/n/ac standards. It is enough to lose direct visibility between the tablet and the head, or move 5 meters away, and DIS will lose connection.
So what to do?
The main difference for us between the diagnostic interfaces (heads) of the MoDiC 3 and Group Tester One devices is that the orange head (MoDiC 3), for a wired connection, uses the RS-232 standard (COM port), and the yellow head (GT1) Ethernet standard. The usual network cable. Which has great backward compatibility. We will use it.
DIS has many ways to communicate with the yellow head, but we are only interested in the direct method of communication via a network cable. Since this is the only possible way to connect the yellow head to the DIS installed on the VMware virtual machine.
Our task — is to connect the yellow head to the computer via Wi-Fi, but at the same time make DIS think that we are using a network cable.
It is enough to connect a router to the end of the Wi-Fi network cable and transmit data packets over the air. And thanks to the versatility and backward compatibility of Ethernet, you can use the latest Wi-Fi standards 802.11/n/ac. This will allow you to get a reliable wireless connection even tens of meters between the yellow head (GT1) and a computer with DIS installed on a VMware virtual machine. DIS will not even know about the additional node on the network and will assume that we are still using only the network cable.
Data packets can even be transmitted over the Internet, allowing thousands of kilometers to be located between the EDIC diagnostic interface and the DIS computer. The main thing is not to go beyond TTL.
In fact, the COM port can also be made wireless by using two Wi-FI or Bluetooth converters in between. According to the diagram: orange head <—> converter <—> air <—> converter <—> laptop with DIS. But even via a wired COM connection, connecting the orange head to DIS installed on a VMware virtual machine is an almost impossible task, not to mention attempts to create a wireless connection. MoDiC 3 — is not the best device.
And how to do this?
We buy any miniature Wi-Fi router, for example: TP-Link TP-WR702N, TP-Link TL-MR3020, Mikrotik mAP lite. There is no need to buy a large home router; we still create a compact solution. The router is powered by 5 volts. Therefore, we need any miniature power supply to convert 12V — 5V, with high-capacity capacitors. When starting the engine, the starter consumes a large current and interference, interference and voltage surges appear in the vehicle's on-board network. Without a high-quality power converter, the router will constantly fail, reboot, or even burn out.
To supply 12 volts to the power converter, you can use the unused test connectors on the front side of the yellow head. But for this you will have to disassemble the EDIC and re-solder the wires in order to supply 12 volts to the measuring connectors, which the diagnostic head takes from the car’s on-board network.
We connect: power converter to the router, network cable from the diagnostic head to the router. We configure the router and connect from the computer to the Wi-Fi access point. At the end we get a wireless connection from EDIC to DIS.
This implementation requires minimal intervention into the diagnostic head, but the router and power converter will be located outside the head. For convenience, all components of the Wi-Fi access point were packaged in one box.
How to get rid of the outer box?
It is possible to place all the components inside the diagnostic head, just like the original EDIC. It will require a lot more intervention on the head, but the result will be no Wi-Fi access point components on the outside. I will describe the process of installing the router inside the original yellow Siemens EDIC diagnostic head and its Chinese clone.
Original EDIC diagnostic head
We completely disassemble the yellow head housing and separate the three internal boards from each other.
I purchased Mikrotik mAP lite as a Wi-Fi access point. This is an incredibly small router, probably the smallest one available on the market. Even without disassembling the housing it can fit inside the head housing.
Unfortunately, when assembling the head housing together with the router, it will still touch some elements of the EDIC computer board. Only half a centimeter is missing.
The router still fits, but at a stretch. You can leave it this way, but then during assembly it is possible to remove the elements on the board, or you can disassemble the router case and remove the board. To get those same half a centimeter. That's what we'll do.
We remove the aluminum partition from the head housing die to lower the router board a couple of millimeters lower.
The router is powered by 5 volts. In the case of the router being located outside the head, there are no problems with the size of the 12V — 5V power converter. Inside the head housing, we are severely limited in free space and cannot fit a powerful power converter. Ensuring stable power supply to the router — is the main task of the entire modification of the diagnostic head. Without this, you will not be able to achieve a high-quality wireless connection. We can expect constant glitches, disconnections and router reboots at any sneeze from the car’s on-board voltage. There are no quality miniature power converters on the market. Everything is made in China and in any case the converter will have to be modified with a file yourself.
The diagnostic head has two very powerful and high-quality power supplies. Exactly the same as those used in all stationary computers. Except that the computer power supply converts 220V AC into three DC power rails 3V, 5V and 12V. And the head power supplies convert the constant 12V of the vehicle's on-board network into 3V and 5V DC power buses.
In fact, three yellow head boards are simultaneously involved in voltage conversion, power stabilization, short circuit protection and polarity reversal, and not each separately.
We can easily connect additional consumers to the output buses of the computer power supply: hard drives, floppy drives, coolers, LED strip. The motherboard, processor or video card will not work worse because of this. This is exactly what the power supply is designed for, to power consumers. If only there was enough power.
Diagnostic head — this is essentially a computer. This means that we can also connect our own current consumers to the power supply buses of the diagnostic head. And the head will not work any worse because of this. The head power supplies are designed with a power reserve. The main task — take power from the 5V output bus from the power supply, and not from the power circuit, for example, the processor or RAM. Or the power circuit controlled by the processor. For example, the power of the built-in Wi-Fi card is controlled by the processor. And if the card is not used, the processor turns it off.
We are starting to make room for our router. The original Wi-Fi card is located on the yellow head computer board. Let's disconnect it. The head and the wired connection work without it, and when the network cable is connected, the processor does not even supply power to the Wi-Fi card.
Unscrew and remove the Wi-Fi card pad.
Where can I get power?
By removing the native Wi-Fi card, we freed the power supply of the computer board of the diagnostic head from an unnecessary consumer. It would be logical to take advantage of this and power our router from this board. In this case, you can be sure that the power supply will not be overloaded. Wi-Fi EDIC card and router consume approximately the same amount of current — 250mA.
The 5V bus is available in many unused pins, which were designed to connect various additional modules to the board. For example, the bus goes to the back button of the yellow head.
The choice of where to connect to the power bus will depend only on your experience and the quality of soldering. I decided to use the unused pins to the right of the button connector and routed the router power wires to the back of the EDIC computer board.
That's all?
No. Now you need to take the Ethernet for the router from the head. To remain able to connect the diagnostic head to DIS via a wired connection, you need to connect to Ethernet from one of the head boards. As with the power bus, where you connect will depend only on your experience and the quality of the soldering. I chose the EDIC faceplate with external headers. It is required to completely simulate the use of a network cable. Connect to the 4 signal contacts and make a jumper between the two contacts, thanks to which the diagnostic head computer knows that the network cable is connected to the connector.
We crimp the connector of our internal network cable.
Well, is that all now?
Yes, these are all the necessary changes in the diagnostic interface. You can connect, configure the router and test the modification.
We fix the router in the head housing area. You can use snot, chewing gum, Velcro, magnets, double-sided electrical tape, squeeze between two pieces of foam. Let's use our imagination.
We connect power and Ethernet to the router and assemble the head housing. The modification of the original GT1 diagnostic head is completely completed.
Chinese clone of diagnostic head
The process is not much different from modifying the original head. We disassemble the EDIC clone body and separate the three internal boards from each other.
The quality of the components and assembly of the Chinese yellow head is an order of magnitude lower than the original from Siemens. I purchased a TP-Link TL-MR3020 as a Wi-Fi access point. The dimensions of the router are much larger than the Mikrotik mAP lite, so we immediately disassemble the case.
Unsolder the Ethernet and USB type A connectors from the router board. Without this, it will not fit in the head housing. We solder the Ethernet signal wires directly to the contacts on the board. We leave Mini USB to power the router.
We remove the aluminum partition from the head housing strip to free up even more space.
The power supplies on the two boards of the Chinese head are similar in power to the original one.
Since the Chinese clone computer board does not have a Wi-Fi card, many components and consumers that are present in the original head, it makes sense to connect to the 5V bus from its power supply. Moreover, there are more places for possible connections on this board..
As with the original head, I used the unused pins to the right of the button connector and routed the router power wires to the back of the GT1 computer board.
I also wired the network cable on the front board of the diagnostic head with external connectors. But the soldering was done in a different place.
We connect, configure the router and assemble the head housing. Modification of the Chinese clone is completely completed.
I did not get anything 
Then we send the head by mail to me, a week later we pick it up ready and configured. Or we buy ready-made. Without understanding, it is easy to break, and repairing such a device is unrealistic. Meow.
