That 2002 Ford Explorer took me 6 hours for a simple no-start

I was working on this old Explorer last Tuesday, customer says it cranks but won't fire. Checked spark, fine. Fuel pressure, fine. Spent 2 hours chasing my tail before I remembered the PATS system on these. Pulled the key apart and the transponder chip had cracked in half. A $12 part and 20 minutes later it fired right up. Has anyone else ever had a simple problem turn into a whole day because you overlooked something obvious?

3 comments

3 Comments

james_kim1mo ago

A simple problem turn into a whole day" - that PATS system is the worst. I've been there with a Ford Focus that wouldn't start just because of a dead battery in the key fob. It's always the simple stuff that gets you.

cameronschmidt1mo ago

Dude I spent like 4 hours on a 2005 Mustang once because of that exact stupid PATS issue. Found out it was just a weak coin battery in the key fob after I had already pulled half the dash apart.

the_ruby26d ago

And here's the part that really gets me about PATS - nobody ever talks about how it can fail in the weirdest ways when the car has been sitting for a while. I had a Lincoln LS that would start fine for a week, then suddenly refuse to crank, and I'd find the PATS light flashing. Turned out to be a corroded ground wire under the carpet near the door sill, not even related to the key or the transceiver ring. The moisture from a leaking door seal had worked its way into the harness connector, and it was creating just enough resistance to confuse the system. So yeah, you're right that it's usually the battery in the fob or something dumb like that, but sometimes it's a completely stupid environmental thing that you'd never think to check.