Blowing O2 Fuse

[Rustbucket350]

2000 Ranger 2.5. When I turn the ignition on it'll blow the O2 fuse in the power distribution box immediately. I unplugged everything on that circuit and it still blows. However, if I unplug the large plug between the power distribution box and engine harness/pcm it doesn't blow the fuse. I'm not sure if it's a wiring short or a pcm issue.

 

[PetroleumJunkie412]

Have you considered pouring your truck a cup of tea and asking it what's wrong?

 

[PetroleumJunkie412]

In all sincerely, it sounds like a short, but I have no idea.

Someone far more knowledgeable than I will be along.

 

[RobbieD]

Harness going to the sensor may have come loose and melted on an exhaust pipe. Worth crawling under and check the wiring.

 

[Uncle Gump]

Did you R&R the engine or transmission?

Pinched the harness between the two?

 

[Vindictus]

Have you considered pouring your truck a cup of tea and asking it what's wrong?

my Ranger only responds if it's a beer

 

[PetroleumJunkie412]

my Ranger only responds if it's a beer

AAAAAAAAAA INTERLOPER

 

[Rustbucket350]

I checked the harness for burns but didn't see anything worth cutting the loom open. I'll have to take a closer look. No wires are pinched and it just randomly started blowing the fuse out of the blue. I was hoping for a way to isolate the pcm or harness to narrow it down further. Not sure if it's even possible to test the pcm.

 

[Rustbucket350]

Well I found that one of the two grounds on the firewall by the pcm had a short somewhere invisible. Ended up just unhooking it and everything seems to work fine with no codes. I can't explain it and I have no idea what that ground is for.