Experiencing trouble connecting your scan tool to your 1999 Jeep Cherokee’s OBD2 port? A non-functional OBD2 port can prevent you from diagnosing check engine lights and other critical vehicle issues. Fortunately, it’s often a simple fix involving checking the power and ground connections to your Diagnostic Link Connector (DLC). This guide will walk you through the steps to troubleshoot a dead OBD2 port on your 99 Cherokee.
First, locate the DLC, typically found under the dashboard on the driver’s side. The most common culprits for a non-responsive OBD2 port are power or ground supply problems. Let’s begin by checking these essential connections.
To test for power, you’ll need a voltmeter. Identify the DLC pin cavities: on the top row, the second and third cavities from the left are ground pins. On the bottom row, the far right cavity is the 12VDC power supply.
Using your voltmeter, measure the voltage between one of the top row ground pin cavities and the bottom row power pin cavity. You should see a reading of approximately 12 VDC. If you don’t get a reading, try the other ground pin cavity. Still no power? Inspect the ground wires connected to the oil dipstick tube mounting bracket stud on the engine’s left side. Ensure these wires are securely attached and free from corrosion. If they appear intact, use an ohmmeter to check continuity between each ground pin cavity and chassis ground. You should see very low resistance (0.5 Ohms or less), indicating a good ground connection.
If the ground connections are solid, the next step is to check the power supply. The OBD2 port receives power from fuse F17 in the Power Distribution Center (PDC). While a blown F17 fuse would likely affect other systems like the headlamps, it’s worth verifying. Locate the PDC (usually under the hood) and check fuse F17 for any signs of damage.
Finally, visually inspect the pin cavities within the DLC itself. Look for any corrosion or signs of expanded pins, which might occur if someone has used oversized probes in the past. Corrosion can impede electrical contact, and expanded pins might prevent a proper connection with your scan tool.
By systematically checking the power, ground, fuse, and connector condition, you can often resolve OBD2 port issues on your 1999 Jeep Cherokee and get back to diagnosing your vehicle effectively. If these steps don’t resolve the problem, more complex communication issues within the vehicle’s systems might be at play, requiring further diagnostic investigation.
