All of a sudden on my way home tonight in the dark my instrument panel lights didn't come on. I could tell my head lights were working. Someone told me behind me my lights were off. When I got home I noticed also my tail lights and parking lights were also not working. I thought if the headlight switch was out only the headlights would be out. I checked a couple fuses for the instrument panel and they were all good. I replaced the headlight switch a few years ago because the head lights did indeed quit working but I've never had any issues before. I haven't messed with anything recently. What could be going on?

 

Just a long shot here....really just a WAG:
Inspect the wiring harness that plugs into your headlight switch. Perhaps it got warm, melted the plastic harness and now the pins have poor connection.

 

If fuses check ok, check the taillights Ground connection & their electrical connector back there. If you have a trailer light pigtail, where it plugs in to the vehicle wiring is the connector I'm thinking of. Try a wiring & electrical connector wiggle test back there. Check the connector pins / sockets for corrosion & loose fit, Check the splices & ground connections. If you have B+ to the lamps, its a ground problem. If no B+ to the lamps, then you have a wiring run B+ feed problem, from under hood to the taillights. There are a couple of splices & electrical connectors in the taillight wiring run on the drivers side along the frame rail, so check them from back to front see where the B+ feed stops, then inspect that wiring run, electrical connector, or splice for problems & let us know what you find.

 

Checked the power distribution fuses with a test light before I decided to tear the cluster bezel apart to change the headlight switch. Even though the switch was under warranty I decided it would be a whole lot easier if a fuse was out. Luckily it was just a blown fuse in the power distribution box. I've never had to change any fuse on this truck so they are all original. They all work now.

 

Ok blown fuse, so an overload of some kind caused it to blow & sometimes when a lamp element burns out it'll cause a fuse to blow, so make sure the brake Stop lamps on both sides light up ok. You can do that without a helper by turning the emergency flashers on while you walk back there to make sure both stop filaments are lit as they blink.

 

Well I thought it was just an old fuse since it was the original one. I just checked to see if everything was working but never really drove it at night until this week. It worked a day ago driving home and tonight it blew a few minutes into the drive home. It's a 15 mile trip home so I stopped and tried to swap the fuse just enough to get home but it blew right away. I had to use my radio fuse and it blew it. I tried it again when I got home to see what happens when I just turn it to parking lights after I replaced the fuse. It was dark at home so when I turned the switch on I could see the fuse blow in the junction panel under the hood. All the brake lights work, turn signals, headlights. Parking, instrument panel lights, license plate, and tail lamps do not work. How do I figure out what's wrong? I'm wondering if the headlight switch is bad. A similar situation happened the last time the headlight switch went out a few years ago.

 

With it blowing the circuit fuse, it suggests you have a short to ground in the B+ circuit. So to save money & your senses, come by, configure & install a circuit breaker of the same amperage specified for the circuit in your owner manual, while your trouble shooting the circuit.
Look for any place the B+ feed wire comes close to & rubs metal, or something hot. You could get underneath on the drivers side & begin disconnecting electrical connectors along the way, to see where it stops tripping the circuit breaker. You could buy a 12 volt buzzer, beeper or other type sounder thats loud enough to hear & install it in place of the fuse, while you wiggle the wiring run, or disconnect the wiring run electrical connectors & listen for the sounder to go quiet, to isolate the faulty wiring section.
If you've done any work around the tranny, like take it out & put it back, the taillight wiring runs up by it on the drivers side. If you have a trailer light plug, be sure to check its wiring, & electrical connector, as they've proven to be good suspects over the years.
The radio fuse isn't high enough amperage to carry the lighting electrical load, so no surprise it blew right away. DON'T over fuse the circuit either, as that could damage wiring, electrical connectors, or start a fire.
More trouble shooting thoughts for consideration, let us know what you find.