The OBD2 port on my 2003 Chevrolet Trailblazer EXT LT isn’t working consistently. A borrowed scan tool, known to function correctly with other vehicles, won’t power on or link to my Trailblazer. An AutoZone scan tool also failed to connect. The issue seems related to the ignition switch; jiggling the key sometimes briefly powers the port, but this is unreliable. An AutoZone employee suggested a faulty computer might be the problem, but also acknowledged the ignition switch as a possible cause. Past experience with a Volkswagen Jetta points toward the ignition switch as the likely culprit.
Further symptoms include a rough idle and poor fuel economy, suggesting a possible misfire. Before delving into more complex diagnostics, I plan to check the under-dash connectors for tightness. Has anyone else experienced similar OBD2 connection problems with a 2003 Chevrolet Trailblazer EXT LT? Could a faulty ignition switch cause these issues, or is a bad computer more likely? Any insights into troubleshooting this problem would be greatly appreciated.
While the ignition switch seems like a plausible explanation for the intermittent OBD2 connection, it’s essential to systematically rule out other possibilities. Loose or corroded connectors at the OBD2 port itself, or within the wiring harness, could also cause intermittent connectivity. Checking the fuses related to the OBD2 system and the ignition system is another crucial step.
A faulty computer (PCM – Powertrain Control Module) could indeed be the root cause, but it’s usually less common than simpler issues like wiring problems or a bad ignition switch. Diagnosing a PCM issue typically requires more advanced tools and expertise. If basic troubleshooting steps don’t resolve the problem, consulting a qualified mechanic specializing in Chevrolet vehicles is recommended. They can perform a thorough diagnostic scan, pinpoint the exact cause, and recommend the appropriate repair. Addressing the underlying issue causing the OBD2 connection problem is vital, as it hinders the ability to retrieve diagnostic trouble codes (DTCs) necessary for identifying and fixing the rough idle and poor fuel economy.
