2002 F150 SuperCrew XLT 4.6L here. Service engine soon light came on <24hrs after replacing wheel bearing and fuel filter. Running fine, but unable to get a diagnostic tool to read the code. Advanced Auto tried and told me that the under dash #3 relay that runs the 2nd cigarette lighter and the OBD II Port isn't working right. Actually, the relay isn't even there for position #3. Attempted to put a new relay in place, but there aren't any connectors behind the panel for the relay to attach to. Should a relay be there in position #3? Other ways to troubleshoot the diagnostic? Any ideas?

Thanks in advance!

 

Install fuse #3, a 20 amp fuse..
There is no relay involved.
Look at page 207 in owner manual.
Good luck.

 

Fixed. I feel dumber now, but fixed. I had it in my head that I was missing a relay in position 3, as that's what the AdvancedAuto rep. said. He even had the same truck. Thanks for the help!