Experiencing issues with your OBD2 port on your 1997 Mitsubishi Eclipse and suspecting a power supply problem? You might be on the right track! If you’re scratching your head trying to figure out why your scan tool won’t power up, or you’re getting a “no communication” error, the culprit could very well be a blown fuse in your 12V power supply circuit for the OBD2 system. And sometimes, the root cause can be surprisingly simple, even stemming from a DIY repair gone slightly wrong, as I recently discovered.
Like many car enthusiasts, I prefer to get my hands dirty and tackle repairs myself whenever possible. Recently, I was chasing down a persistent vacuum leak in my ’97 Eclipse. The hunt led me to remove the upper air intake manifold to get better access. Everything was going smoothly until it started to get dark. Instead of calling it a night and resuming the job the next day, I decided to push through and finish the reassembly using just the flashlight on my phone. Famous last words, right?
During the reinstallation of the air intake manifold, there’s a crucial ground wire that bolts down along with it. This ground is essential for various electrical circuits, and as it turns out, potentially for your OBD2 port’s 12V power supply. The ground wire in question is a black wire with a small black box connector, located near the lower right bolt of the air intake manifold. You can see it circled in red in the image below:
In my haste and dim lighting, I made a critical mistake. Without realizing it, as I tightened the bolt, the ground wire slipped between the manifold and the intake. Initially, everything seemed fine. The car ran perfectly for a couple of days. However, the engine heat, over time, began to melt the wire’s insulation, eventually leading to a short circuit. Luckily, the short manifested itself while the car was parked in my driveway.
The symptom? My OBD2 port suddenly lost power. My scan tool wouldn’t light up, and any attempt to communicate with the car’s computer failed. After some head-scratching and troubleshooting, I traced the issue back to a blown 30M PCM fuse. This fuse, among other things, is responsible for providing 12V power to the OBD2 system.
The culprit was clear: the damaged ground wire I had inadvertently pinched during reassembly. The short circuit caused by the melted wire had blown the fuse, cutting off the 12V power supply to my 97 Eclipse’s OBD2 port.
The fix was straightforward: replacing the blown 30M PCM fuse and, more importantly, properly securing the ground wire, ensuring it wasn’t pinched or damaged. A simple mistake on my part caused a temporary headache, but thankfully, the damage was minimal and easily rectified. The only cost was the price of a new fuse – around $6 – and a valuable lesson learned about patience and careful reassembly, especially when dealing with ground wires in automotive electrical systems.
So, if you’re facing a dead OBD2 port on your 1997 Mitsubishi Eclipse, particularly after recent engine work, don’t immediately jump to complex diagnoses. Start with the basics: check your fuses, specifically the PCM fuse related to the 12V power supply. And if you’ve been working around the intake manifold, take a close look at the ground wires. A simple visual inspection might just save you hours of frustration and point you directly to a simple, DIY-fixable problem.
Remember, even experienced DIYers make mistakes. The key is to learn from them and share those experiences to help others in the community. Happy wrenching!
