I bought replacement headlight and foglight bulbs tonight and the headlights work fine, but the foglights never turned on. I know the factory bulb is a 9140, and I've read plenty of people saying to use a 9145 replacement bulb, but after I plugged them in nothing happened on either side. Truck is a 2009. Hard to fathom two foglight bulbs in one package are going to be defective, but I guess it's possible. Has anyone else had this issue?

 

Its most likely a fuse. Did you bother checking them (with a DMM?)

 

How were checking them???

Was the truck off and you just using the head lamp switch?

In some models the ignition has to be ON or the vehicle RUNNING for the fogs to work.....

 

That's exactly what the problem was lol. I felt so embarrassed. My old '05 F150 and Lightning didn't have to be on to have the fogs on so I didn't think about turning on the truck until the next morning. Thanks for the replies, guys.