The OBD2 port in your car is essential for diagnostics and connecting various devices, like plug-and-play GPS trackers. If your OBD2 device isn’t powering on, a common culprit is a blown fuse. This guide will help you locate and check the OBD2 port fuse, ensuring your devices receive the power they need.
When you connect a device to your car’s OBD2 port, you should typically hear a beep or see a light indicating it’s receiving power. If this doesn’t happen, don’t immediately assume the device is faulty. Often, the issue is simply a lack of power to the OBD2 port itself, and the fuse is the first place to investigate.
Initial Checks: Connections are Key
Before diving into fuses, let’s rule out simple connection problems. A loose connection is surprisingly common and easily fixed.
Verify OBD2 Port Connections
If you’re plugging your device directly into the OBD2 port:
- Unplug the device.
- Carefully re-insert it, ensuring it’s firmly and fully plugged into the OBD2 port. Sometimes, it might seem connected but isn’t making full contact.
If you are using an OBD2 extension cable, which can be helpful for discreet installations or when the port is in an awkward location, these additional steps are crucial:
Check the Cable Connection at the OBD2 Port
- Turn off your car’s engine.
- Disconnect the extension cable from the car’s OBD2 port.
- Wait for about 5 minutes.
- Reconnect the cable firmly to the OBD2 port.
- Now, plug your device into the extension cable. Listen for the beep indicating power.
Check the Cable Connection to Your Device
If you still don’t hear a beep:
- Turn off the engine.
- Disconnect the device from the OBD2 extension cable.
- Wait 5 minutes.
- Reconnect the device to the extension cable. Listen for the power-on beep.
Test the Device Directly
To isolate whether the issue is with the cable or the device itself:
- Disconnect the extension cable from both the OBD2 port and your device.
- Plug the device directly into the car’s OBD2 port.
- If the device now powers on and beeps, the problem likely lies with the extension cable or its fuse, not the device itself.
Finding and Checking the OBD2 Port Fuse
If direct connection works, the next step is to check the fuse in your OBD2 extension cable (if you are using one) and then the car’s OBD2 port fuse.
Inspect the Cable’s Fuse (if applicable)
Many OBD2 extension cables include an inline fuse for protection.
- Locate the fuse holder on the extension cable.
- Open the fuse holder cap.
- Remove the fuse.
- Inspect the fuse. A blown fuse will usually have a broken wire inside or appear blackened.
- You can test the fuse with a multimeter for continuity or simply replace it with a new 3A mini blade fuse (commonly available at auto parts stores).
- With the cable connected to the OBD2 port and the device, insert the new fuse into the holder and check for power.
Locate the Car’s OBD2 Port Fuse
If there’s no fuse in the cable, or replacing it didn’t solve the issue, the problem might be with the car’s fuse that powers the OBD2 port.
Finding the OBD2 fuse location:
- Consult your car’s owner’s manual. This is the most reliable way to locate the fuse box and identify the specific fuse for the OBD2 port. Look for fuse box diagrams, often located in the manual’s index under “fuses” or “OBD.”
- Check common fuse box locations. Fuse boxes are typically found in these locations:
- Under the dashboard, often on the driver’s side.
- In the engine compartment.
- Sometimes in the glove compartment or side panel of the dashboard.
- Look for fuse box diagrams. Fuse box covers often have a diagram indicating what each fuse controls. Look for labels related to “OBD,” “Diagnostic Port,” “Accessory,” or sometimes older labels like “Cigar Lighter” or “Auxiliary,” as the OBD2 port is often on the same circuit.
Testing the OBD2 Port for Power
Using a digital multimeter is the most accurate way to check if the OBD2 port is receiving power.
- Set your multimeter to measure DC voltage.
- Locate pins 16, 4, and 5 on the OBD2 port. (Refer to an OBD2 port pinout diagram online if needed).
- Pin 16 is the positive power (12V or 24V depending on your vehicle).
- Pin 4 is chassis ground.
- Pin 5 is signal ground.
- Test for voltage between:
- Pin 16 (positive probe) and Pin 4 (negative probe).
- Pin 16 (positive probe) and Pin 5 (negative probe).
- Expected Reading: You should see a reading close to your car battery’s voltage (around 12V-14V for a 12V system, or 24V-28V for a 24V system).
- Zero Volts: If you get a reading of 0 volts, this strongly indicates a blown fuse or a wiring issue.
If you find 0 volts, re-examine the fuse box for a blown fuse, paying close attention to fuses labeled “OBD,” “Accessory,” or similar. Replace any blown fuses with the correct amperage rating.
Further Troubleshooting
If you’ve checked all fuses and connections, and the OBD2 port still isn’t powering your device, there could be a more complex issue with the car’s wiring or the OBD2 port itself. In these cases, it’s best to:
- Consult a qualified mechanic or automotive electrician for further diagnosis.
- Contact the support team for your OBD2 device, as there might be device-specific troubleshooting steps.
Need More Help?
If you’ve gone through these steps and are still experiencing issues, don’t hesitate to contact support for your device. Providing them with details like your vehicle’s make and model, the last time the device was working, and any troubleshooting steps you’ve already taken will help them assist you efficiently.
Remember to always consult your vehicle’s owner’s manual for specific fuse locations and electrical system information. With a systematic approach, you can often resolve OBD2 port power issues and get your devices working correctly.
