When you plug a device into your car’s OBD2 port, such as a plug-and-play tracker, you expect it to power up immediately. Typically, a beep confirms it’s receiving power. But what if you plug in your device and… silence? No beep, no power – this can be frustrating, but it’s often a simple fix. One of the first questions that comes to mind is: Is There A Fuse For The Obd2 Port? The answer is often yes, and checking this fuse should be one of your initial steps in troubleshooting. This guide will walk you through diagnosing and resolving power issues with your OBD2 port, focusing on fuse checks and other common causes.
Initial Checks: Ensuring a Solid Connection
Before diving into fuses, let’s start with the most basic and frequently overlooked issue: connection problems. A loose connection can easily prevent your device from receiving power.
If you’re connecting your device directly to the OBD2 port, simply unplug it and firmly plug it back in. Ensure it’s fully seated in the port. A slightly loose connection is a common culprit.
Alt text: Locating the OBD2 port underneath the steering wheel column in a vehicle interior.
If you are using an OBD2 extension cable, the troubleshooting process involves checking each connection point separately.
Checking the Cable Connection to the OBD2 Port
- Turn off your engine. Safety first! Ensure the ignition is completely off before working with electrical components.
- Disconnect the extension cable from the vehicle’s OBD2 port.
- Wait for a few minutes. This brief pause can sometimes reset any minor electrical glitches.
- Reconnect the cable to the OBD2 port firmly.
- Listen for the beep. If you hear your device beep upon reconnection, it indicates that power is now being supplied, and the issue might have been a loose connection.
Checking the Cable Connection to the Device
If you still don’t hear a beep after checking the OBD2 port connection, the next step is to examine the connection between the extension cable and your device.
- Engine off. Again, make sure the engine is off.
- Unplug the device from the extension cable.
- Wait for 5 minutes.
- Reconnect the device securely to the cable.
- Listen for the beep. If you hear a beep now, the problem was likely a poor connection between the cable and the device.
Verifying the Device Functionality
To isolate whether the problem lies with your device or the cable/OBD2 port, try connecting the device directly to the OBD2 port, bypassing the extension cable altogether.
- Disconnect the cable from both the OBD2 port and the device.
- Plug the device directly into the vehicle’s OBD2 port.
- Listen for the beep. If the device beeps when directly connected, it means the device itself is working correctly. In this case, the issue is likely with the extension cable or potentially the OBD2 port fuse we’ll investigate next.
Is There a Dedicated Fuse for the OBD2 Port? Checking the Fuses
Now we come to the crucial question: is there a fuse specifically for the OBD2 port? Yes, in most vehicles, the OBD2 port is indeed protected by a fuse. If your device isn’t powering up, a blown fuse is a very common reason. This fuse is often part of a circuit that also powers other components, such as the cigarette lighter (now often called the auxiliary power outlet) or interior lights.
Examining the Cable Fuse (If Applicable)
Some OBD2 extension cables come with their own inline fuse. If you are using a cable, check if it has a fuse holder.
- Locate the fuse holder on the extension cable.
- Open the fuse holder cap to access the fuse.
- Inspect the fuse. Look for a broken filament inside the fuse. If it’s broken, the fuse is blown and needs replacement.
- Replace the fuse. Typically, these cables use a 3A mini blade fuse, readily available at auto parts stores. Ensure you replace it with a fuse of the same rating.
- Test again. With the new fuse installed and the cable connected, check if your device now powers on.
Alt text: Close-up of a mini blade fuse being inserted into a fuse holder for automotive electrical protection.
Checking the Vehicle’s OBD2 Port Fuse
If the cable fuse is not the issue, or if you are not using a cable, the next step is to check the fuse in your vehicle’s fuse box that powers the OBD2 port.
- Locate your vehicle’s fuse box. The location varies by car model, but it’s often under the dashboard, in the glove compartment, or under the hood. Consult your car’s owner’s manual for the exact location and fuse diagram.
- Identify the OBD2 port fuse. Refer to the fuse box diagram (usually printed on the fuse box cover or in your owner’s manual). Look for labels like “OBD,” “Diagnostic,” “Accessory,” or sometimes still “Cigarette Lighter.” The owner’s manual is your best resource here.
- Inspect the fuse. Remove the identified fuse using a fuse puller (often found in the fuse box). Visually inspect the fuse for a blown filament.
- Test with a multimeter (recommended) or replace. For a definitive check, use a multimeter to test for continuity across the fuse terminals. If there’s no continuity, the fuse is blown. Alternatively, you can try replacing it with a new fuse of the same type and amperage rating.
- Replace the fuse. If blown, replace it with a fuse of the correct amperage. Important: Never use a fuse with a higher amperage rating, as this can damage your vehicle’s electrical system.
- Test the OBD2 port again. After replacing the fuse, plug in your device and check if it now receives power.
Testing the OBD2 Port with a Multimeter
For a more precise diagnosis, you can use a digital multimeter to directly test the power at the OBD2 port. This will confirm if the port is receiving power and ground correctly.
- Set your multimeter to DC Voltage mode.
- Locate pins 16, 4, and 5 on the OBD2 port. Pin 16 is the power pin, pin 4 is chassis ground, and pin 5 is signal ground. OBD2 ports are trapezoidal, making pin identification straightforward.
- Connect the multimeter. Connect the red lead (positive) of the multimeter to pin 16. Connect the black lead (negative) to pin 4 (or pin 5 for signal ground – either ground pin should work for a basic power test).
- Check the voltage. Turn your ignition to the “ON” position (you don’t need to start the engine). The multimeter should read approximately 12 volts (or your vehicle’s battery voltage).
- Interpret the results.
- 12V reading: Indicates the OBD2 port is receiving power and ground. The issue is likely not a blown fuse or lack of power to the port itself.
- 0V reading: Suggests there is no power reaching the OBD2 port. This strongly points to a blown fuse or a wiring issue upstream of the port. Double-check the fuses again if you haven’t already, and consult a professional if fuses are not the problem.
Testing car fuse with multimeter
Still Having Issues?
If you’ve checked all connections, examined the cable fuse (if applicable), confirmed the OBD2 port fuse in your vehicle’s fuse box, and even tested the port with a multimeter, and your OBD2 device still isn’t powering up, then there might be a more complex issue. It’s possible there’s a wiring problem, an issue with the OBD2 port itself, or a less common fuse problem.
At this stage, it’s recommended to contact support for your OBD2 device or consult a qualified automotive technician. They can perform more in-depth diagnostics to pinpoint the exact cause of the problem.
When contacting support, have the following information ready to help them assist you efficiently:
- Vehicle make and model
- Date and time of last successful device report (if applicable)
- On-site contact person (if relevant for fleet vehicles)
- Location for technician dispatch (if needed)
Need More Assistance?
Contact Support for further help and troubleshooting.
Related Articles:
- Why is my vehicle not reporting?
- Discover plug and play (OBD-II) vehicle tracker compatibility
- How to install plug and play (OBD-II) vehicle trackers
