Disassembling the ELM327 Cable is the first step. Remove the sticker and unscrew the four screws holding the enclosure together using a small star screwdriver. Carefully remove the circuit board.
Tip: Before removing the connector that attaches to the OBD2 port, mark one side with nail polish. This helps ensure correct reassembly as the connector can be inserted in either direction. Although not necessary for this project, knowing the connector orientation is always beneficial.
Next, solder two wires to the TX (transmit) and RX (receive) pins on the ELM327 board. Refer to the provided image for the pinout information of the USB bridge chip. Exercise caution while soldering to avoid accidentally detaching components.
Tip: To identify the TX pin, program an Arduino to send data to the serial monitor with short delays. Connect a jumper wire to the Arduino’s TX pin and probe the ELM327 board. Observe the surface-mounted LEDs; they will flicker when communication occurs. This method won’t work for the RX pin, but its location is easily identifiable in the provided image.
Important: The USB cable connects to the board via a 4-pin connector. Cut the middle two wires to prevent the ELM327 from communicating with the PC while connected. This ensures the ELM327 receives power from the PC’s USB port without the serial controller being occupied, allowing the Arduino to communicate with it.
Finally, reassemble the ELM327. Secure the board within the enclosure, or if space is limited, consider alternative mounting solutions as shown below.
