Chapter VIII: How I built my own OBD2 Wi-Fi Adapter

So, I did something I never thought I’d do: I built my own OBD2 Wi-Fi adapter. Yep, I’m officially that person now. It’s not quite as glamorous as building your own robot or designing a time machine (which, let’s face it, would be cooler), but it’s still pretty satisfying to create something by myself. Well, maybe “talk” is a stretch—it’s more like it grunts back in mechanical language, but I’ll take it.

You might be thinking, “Why go through the hassle of building this when you can just buy one online for like, 20 bucks?” And yeah, I hear you, but that’s kind of the point. Where’s the fun in just buying something off the shelf? Plus, working with car diagnostic and communication, the niche "flex" of my workplace is to actually have one and built it yourself. I just stepped up you know.

What Exactly Does This Thing Do?

In case you’re not familiar with OBD2 adapters (and let’s be real, most people aren’t), it’s basically a little gadget that lets your car communicate with your computer. It plugs into the OBD2 port (On-Board Diagnostics), and then connects to your car.

I already had a physical cable for the purpose. This does the same thing but in a cooler way.

Building It: The Fun and the Fury

Now, let’s not pretend it was all smooth sailing. There were a few moments during the build where I thought I’d fried the whole thing. This little device works with 2 different voltages, the 12V coming from the vehicle low-voltage battery, and the 5V to power the systems inside the adaptor. I had to be careful to solder correctly the 12V-5V transformer because I could have burned the Wi-Fi card instantly.

After getting all the components together, the most satisfying part was watching the blue Wi-Fi connection light blink for the first time. It was like my little device was saying, “Hello world,” only it was more like, “Hey, I’m ready to tell you why the software in the car is not working”.

Materials and Build Process

For the more tech-savvy folks out there, I’ll include some details about the components and how I soldered them together. For the rest, I’ll keep it simple—you know, to avoid scaring anyone away.

Material:

• OBD2 Connector: to connect to the car.
• 12V-5V Converter: to convert the voltage coming from the car low-voltage battery and power the 5V elements.
• Wi-Fi Card: to transmit or receive the signal with your computer.
• Power and Ethernet Cables: to connect everything together.
• Ethernet connector: to connect the OBD2 pins to the Wi-Fi card.
• Power Switch button (Optional): to open and close the power circuit.
• Fiber Optic (Optional): to transfer the Wi-Fi Card light and see it from the outer case.

Build Process:

There are no proper instructions for this. First of all, get yourself an OBD2 pin map so you can understand what pin does what. The power pins from the OBD2 need to be connected to the 12V-5V transformer. The output voltage from the transformer is then correct to power the Wi-Fi card. Ethernet cables go instead directly from the OBD2 pins to the Wi-Fi card.

Adding a power switch button adds a little bit of complexity to the system. As you can see from the figure below, the power cables from the OBD2 pins go first to the button and then to the transformer. The button will cut the power if not clicked.

Right, I was almost forgetting that you will need a soldering machine for the job.

Wrapping Up: Was It Worth It?

In the end, was it worth the effort? Absolutely. I now have an OBD2 Wi-Fi adapter that’s not just functional but also custom-built by yours truly. Sure, it might’ve taken me a bit longer than buying one, and I may have learned a few choice words along the way (not going to lie, there was cursing involved). But hey, now I've gained the respect of the other Integration Testers, it feels like a victory.

Plus, let’s not underestimate the cred that comes with saying, “Oh yeah, it's Wi-Fi and I built that myself.”

Ciao ciao! Feel free to add your comments!