What would cause the parking lights to stay on even if the truck is not running. the light switch is in the off position.

If you pull the 20amp park lamp fuse and the lights stay on, it almost has to be a short inside the headlight switch.
Will the lights go off if you unplug the headlight switch ?

are you sure you're not looking at the running lights? the running lights on the rear and the daytime running lights on the front are suppose to come on when the car is in gear and go out when the car is in park.

Brake Light Switch REMOVAL & INSTALLATION

1. Disconnect the negative battery cable.
2. Disable the SIR system (if equipped).
3. Remove the clip (R/V Series) or unclip the switch (C/K Series) and unplug the electrical connector from the brake light switch.
4. Remove the switch.
5. Installation is the reverse of removal.

running lights are designed to be on whenever the key is in the "on" position. Your "lights" switch may also turn them on, but it is a separate circuit.

Check your DOME light switch. There are 3 positions. Completely OFF even with doors open, ON with doors shut so you can read while parked, NORMAL for the lights to come on only when the doors are open.

Your headlight switch will also turn everything ON inside when it is turned completely to one side. Just twist this switch a little towards center if this is on.

do you have a trailer hitch with a wiring convertor box when these malfunction you have some crazy problems,if not you may have a broken solder joint on the steering column switch i have seen this before

Get under the dash ad look at your brake pedal lever. You will see a stop light switch that screww into a bracket with a 'button' sticking out of it. if pulling up on the brake pedal (even slightly) solves your problem, then the switch needs adjusting closer to the brake lever. If adjusting does not stop problem then replacement of brake light switch may be required.

190e light switch turned counter clockwise all the way to the left is for left front and rear parking light.turn switch clockwise 1 position and the right parking and tail light will be on,turn 1 more position clockwise and all lights will be off. if lights continue to be on replace light switch

Have you checked the alternator fuse? The regulator needs power from the fuse to turn on the alternator. The old alternator could have blown the fuse.

hiya if the rear lights are remaining on ? with no ignition it will be the brake lights staying on this is easily remendied/ checked by trypulling the brake pedal up by hand and see if lights go off ? if so then you will need to adjust the b/light switch which is positioned adjacent to pedal and can be screwed inwards towards the pedal untill the plunger on switch is pushed into the switch which puts lights off ensure pedal is fully up then adjust switch reconnect the wire/plug and press pedal slightly to ensure b/lights operate ok and then go off with pedal released ? on hyundai the brakelights do not req ignition on to operate hence more likely problem is as above good luck