what would cause this
here goes; 95 f150 4x4. if you turn on the lights,the running lights will not work. if you turn it to running lights only, they work fine. signals and brake lites are fine. in other words,you have to choose between headlights or running lites. switch is new so are bulbs and fuses
If the lights do not work as before and the switch is new check a wiring diagram and see if there is a relay somewhere which may be defective.
Search Ford F-150 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Ford F-150 Experts