For users of devices like the Auto Car V1 4 ELM327 OBD2 Bluetooth diagnostic adapter, managing power consumption is a key consideration. Many prefer that these adapters only draw power when the vehicle is running to prevent battery drain. This guide details a simple modification to switch the power source of your ELM327 OBD2 adapter from constant 12V to switched Accessory (ACC) 12V. This ensures the device is only active when the ignition is on or in ACC mode. This modification, demonstrated here on a BAFX Products PIC18F2480 Bluetooth OBD2 adapter, is straightforward and can be completed in about 15 minutes.
Here’s how to modify your ELM327 OBD2 adapter for switched 12V power:
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Access the Internals: Begin by removing the blue label on your adapter to reveal the four screws holding the case together. Unscrew these to open the unit.
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Disconnect the Connector: Carefully separate the two halves of the adapter case. Inside, you’ll see a white connector linking the OBDII connector to the PC board. Gently unplug this connector.
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Remove OBDII Connector: With the white connector detached, you can now lift the OBDII connector assembly completely out of the adapter’s housing for easier access to the wiring.
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Reposition the Power Wire: Identify pin 16, which carries the constant 12V power, and pin 8, designated for switched ACC 12V. In most adapters, pin 16 is located on the top left and pin 8 on the bottom left, making this a simple wire move. Carefully move the wire from pin 16 to pin 8.
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Reassemble Connector and Unit: Place the OBDII connector back into the housing and reconnect the white connector to the PC board, ensuring it is firmly seated.
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Close the Casing: Reassemble the two halves of the case and secure them with the four screws. Be mindful of the internal LEDs to avoid bending them during reassembly.
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Final Touches: Replace the blue label if desired, or leave it off. The modification is now complete.
Your Auto Car V1 4 ELM327 OBD2 adapter will now only power on when your vehicle is on or in ACC mode. This switched power modification effectively prevents unnecessary battery drain while maintaining full diagnostic functionality when you need it. This setup is confirmed to work seamlessly, including with applications like Turbo3’s App, ensuring reliable performance and efficient power management for your automotive diagnostic needs.
