Hi there y'all. I'm 72, a handy-man, and a decent body guy that learned from my dad (37 years Chrysler Local 444). My 2002 F150 King Cab has a problem that is odd. I'm going to note that I bought a new battery and recently drove 'Bluto' 1700 miles from Canada to SoCal where I'm retiring.
Electrical issues with me are always heads scratchers.
I just bought 2 Headlamps (one had died and both were beyond shining up.) They were plug n play... no issues. However, when I try to use them, both Lowbeams and the Driver's Side Highbeam do not go on.
Since this is electrical, I'm going to mention that after 1600 of those 1700 miles here, the A/C fan cuts out... apparently intermittently.
.......perhaps related?

Thx for reading, Ron

 

Check fuses and/or relays, or loose wire connectors.

 

Was everything clean (non-corroded)? I would start by double checking everything and cleaning all of your connections and then move on to grounds and wiring.

 

Welcome.
Try posting your issues in the ( 1997 - 2003 Ford F150 ) section of the site..
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Welcome to the forum Ron. To state the obvious did you check the bulbs, as stated above also check the plug connections at the headlamps. If they were working fine before removing the old ones & now no low beams those are the only 2 things I can think of.