For BMW owners and automotive enthusiasts keen on diagnostics and coding, an OBD2 to Ethernet cable, often referred to as an ENET cable, is an indispensable tool. While purchasing one might seem like the easiest option, import restrictions or immediate needs can sometimes make it challenging. If you’re facing such hurdles, or simply enjoy a good DIY project, creating your own ENET cable at home is surprisingly straightforward and cost-effective. This guide will walk you through the process, ensuring you have the necessary cable to connect your BMW to your laptop for coding and diagnostic purposes.
Materials You’ll Need to Build Your OBD2 to Ethernet Cable
Before you begin, gather these readily available components. You can often find these at online retailers or electronics supply stores. Having everything on hand will streamline the cable-making process.
- Soldering Iron Kit: Essential for creating secure and lasting electrical connections.
- Multimeter: A crucial tool for testing resistor values and ensuring correct connections.
- Ethernet Cable (10 Feet): A standard Cat5e or Cat6 Ethernet cable will work perfectly.
- OBD2 Connector (16-Pin Male): This connector interfaces with your vehicle’s OBD2 port.
- 510 Ohm Resistor: A key component for proper circuit function in ENET cables.
- Wire Strippers/Cutters: For preparing the Ethernet cable wires.
Optional but Recommended:
- Cable protector and boot for a professional finish and added durability.
Step-by-Step Guide to Creating Your ENET Cable
Follow these detailed steps to assemble your OBD2 to Ethernet cable. Accuracy in wiring is critical for the cable to function correctly and avoid any potential issues with your vehicle’s electronic systems.
Step 1: Prepare the Ethernet Cable
Begin by cutting your Ethernet cable in half. Decide on your desired cable length before cutting. If using a cable protector and boot, slide these onto one end of the cut Ethernet cable now. This is much easier to do before wiring.
Step 2: Expose and Prepare the Ethernet Wires
Carefully remove the outer plastic jacket of the Ethernet cable end to expose the internal wires. You’ll see eight wires, each with a different color, twisted in pairs. Untwist these pairs. For this ENET cable DIY, you will only need specific wires. Identify the following wires based on the 568B standard (commonly used):
- White/Orange
- Orange
- White/Green
- Green
- Brown
The Blue, White/Blue, and White/Brown wires are not needed for this application and can be trimmed back to avoid confusion. Once identified, use your soldering iron to “tin” the exposed ends of these five wires. Tinning involves applying a small amount of solder to the wire ends, making them easier to solder to the OBD2 connector pins and preventing fraying.
Step 3: Open the OBD2 Connector
Gently open the OBD2 connector housing. It usually snaps open or has small screws. Inside, you’ll see 16 pins, numbered 1 to 16. Refer to the pinout diagram in Step 5 to understand which pins you’ll be soldering to.
Step 4: Verify the Resistor Value
Before soldering the resistor, use your multimeter to check its resistance. Set your multimeter to measure resistance (Ohms – Ω). The resistor should ideally measure close to 510 Ohms, with a tolerance range of approximately 506-560 Ohms. This ensures it’s within the correct specification for the ENET cable.
Step 5: Solder the Wires and Resistor According to the Pin Diagram
This is the most crucial step. Carefully solder the tinned Ethernet wires to the OBD2 connector pins according to the following diagram:
| Ethernet Pin | Wire Color | OBD2 Pin |
|---|---|---|
| Pin 1 | White/Orange | Pin 3 |
| Pin 2 | Orange | Pin 11 |
| Pin 3 | White/Green | Pin 12 |
| Pin 6 | Green | Pin 13 |
| Pin 8 | Brown | Pin 4 & 5 |
Important: Pins 4 and 5 on the OBD2 connector are typically ground pins and are bridged together. Solder the Brown Ethernet wire to both Pin 4 and Pin 5.
Next, solder the 510 Ohm resistor between Pin 8 and Pin 16 of the OBD2 connector. Pin 8 is already connected to the Brown Ethernet wire.
Step 6: Final Assembly and Testing
Once all soldering is complete and you’ve allowed the connections to cool, carefully close the OBD2 connector housing. Ensure no wires are pinched or exposed. If you used a cable protector and boot, slide the boot over the OBD2 connector end for a clean and durable finish.
Your DIY OBD2 to Ethernet cable is now ready! Connect it to your BMW’s OBD2 port and the Ethernet port of your laptop. You can now use diagnostic and coding software to communicate with your vehicle’s systems.
By following these steps, you’ve successfully created your own OBD2 to Ethernet cable, saving money and gaining a valuable tool for BMW diagnostics and coding. Enjoy exploring the capabilities of your BMW!
