Experiencing a dead OBD2 port in your 2005 Yukon can be frustrating, especially when you need to run a diagnostic scan. If your OBD2 scanner isn’t powering up when plugged into your Yukon, don’t panic. Often, the issue is simpler than you might think and can be resolved with a few straightforward checks. This guide will walk you through the most common cause of a “no power at OBD2” problem in a 2005 Yukon and how to fix it.
Step 1: Check Fuse 13 in the Underhood Fuse Box
The first and easiest step is to inspect Fuse 13, located in the underhood fuse box of your 2005 Yukon. This fuse is crucial because it powers both the OBD2 port and the cigarette lighter (or auxiliary power outlet). A blown or faulty Fuse 13 is a very common reason for a lack of power at the OBD2 port.
Sometimes, a fuse can appear visually intact even when it’s blown. Therefore, simply looking at the fuse may not be enough. It’s best practice to replace Fuse 13 with a new 20 Amp fuse to rule out a defective or subtly blown fuse. Additionally, check the fuse terminals for any corrosion or dirt, which could also impede the electrical connection.
Step 2: Verify Power at the Cigarette Lighter Port
The cigarette lighter port (or auxiliary power outlet) is on the same circuit as the OBD2 port, powered by Fuse 13. If you’re experiencing no power at the OBD2 port, check if your cigarette lighter port is also dead or significantly underpowered. A healthy cigarette lighter port should register approximately 12V DC. If it’s showing a much lower voltage, like 6V DC as mentioned in some cases, or no power at all, it further points to a problem with Fuse 13 or the shared circuit.
Step 3: Test for Voltage at Fuse 13
If replacing Fuse 13 doesn’t restore power to your OBD2 port and cigarette lighter, the next step is to use a multimeter to check for voltage directly at the Fuse 13 location in the underhood fuse box.
With a multimeter set to DC Volts, ground the negative (black) lead to a metallic part of the vehicle chassis. Then, with Fuse 13 installed, use the positive (red) lead to touch each of the exposed metal terminals on top of Fuse 13. You should read approximately 12V DC on both terminals of the fuse.
If you don’t see 12V DC on either side of Fuse 13, there might be an issue upstream in the power supply to the fuse box itself. If you see 12V DC on only one side of the fuse, but not the other, this confirms that the fuse is indeed blown or there is a problem with the fuse box contacts.
Step 4: Check Continuity Between Fuse Box and OBD2 Port
If you are getting 12V DC at Fuse 13, but still have no power at the OBD2 port, the problem might be a break in the wiring between the fuse box and the OBD2 port connector (pin 16).
To check for continuity, switch your multimeter to Ohms (resistance) mode. Remove Fuse 13 for this test. Connect one lead of your multimeter to the load side terminal of the Fuse 13 socket in the fuse box (the side that was not showing 12V in the previous test). Connect the other lead to pin 16 of the OBD2 port. Refer to the wiring diagram provided earlier to identify pin 16.
A reading of zero ohms or very close to zero ohms indicates good continuity, meaning the wire is intact. An infinite resistance reading (or very high resistance) suggests a break or open circuit in the wiring between the fuse box and the OBD2 port, which will need further tracing and repair.
Conclusion
Diagnosing a “no power at OBD2 port” issue in your 2005 Yukon often starts with checking Fuse 13. By following these steps, you can systematically pinpoint the most likely cause, whether it’s a simple blown fuse or a wiring issue. If you’ve checked these steps and are still facing problems, it might be time to consult a professional mechanic for further diagnosis and repair of your 2005 Yukon’s electrical system. Remember to always prioritize safety when working with automotive electrical systems.
