I have a 99 Ford Ranger XLT four-wheel-drive 3 L the running lights stay on even when the key is off I replaced the ignition cylinder lock and it fixed it for about a week and then it started doing it againAnd now my driver side headlight won’t turn on I replaced the bulb but that didn’t fix it what could it be.Any help would be greatly appreciated.

 

Welcome to the forum

Main light switch is most likely problem, these carry high amps so do fail, it also has power all the time, so not sure why ignition key cylinder would have any effect on it, it has no connection to exterior lights
There is also a Parking Light relay that could stick closed although rare occurrence, the light switch runs the relay not the key
The Keyless entry is also connected to the relay, to flash parking lights when locking or unlocking, which is why the relay was added to the parking lights, so it would be possible, but less likely, for the keyless entry system to cause parking lights to stay on


The main light switch sends power to the Multi-function switch(turn signal stalk) and it send that low beam power to the fuses

Left and right low beams each have their own fuse, fuses #4 and #8 in cab fuse box(10amp), check if one is blown

High beams share one fuse, #33 in cab fuse box

 

Ron Thank you for taking the time to answer my question I will go ahead and check those fuses and swap the switch out thank you