dickchibbles

hello,

i'm new to fords but i have a very strange and bizzare issue going on.
first off I have a 2002 f-150 XLT fx 4X4, great truck lots of fun. HOWEVER here's the strange issue i'm having.

I have a p420 code popping which isn't a big deal (o2 sensor) However My 4wd isn't working. here's what happens.
I start the truck up cold. the check engine light isn't on. i switch into 4wd it doesn't work. it's almost like the switch isn't powered, then the check engine light comes on after driving for a while, I pull over and stop. turn the 4wd switch and it goes right into 4wd. it works fine as long as the check engine light is on.
now here's the weird part. I reset the code (with code reader) to get the check engine light off, and sometimes the 4wd switch doesn't work again until the check engine light comes back on. i mean seriously WTF is going on here???????

HELP !!!!!!! hate to start replacing parts and kind of afraid to put a new O2 sensor or cat in which will fix the p420 code, but possibly end up not having my 4wd work at all. jesus this one is rattling my brain....


THANKS IN ADVANCE..

doctorschlachter

Replace the 02 sensor, and further troubleshoot the 4wd issue.

dickchibbles

I will, figuring out why is the real bizarre issue. It's obviously some electrical issue and not mechanical
Thanks for the input