379 Interior Lights Not Working

I have a '93 379. One morning while I was getting going I realized none of my interior lights were working. These being the reading lights(cab & sleeper), door lights, storage compartment lights, and the fluorescent light on the sleeper wall. They worked the previous night as I was going to bed, and every day before that.

All of my fuses are fine, no issue there. There has to be somewhere that all these lights are fed power from the same source, however, I can't find that place. I have looked at wiring diagrams and can't discern anything from them. I asked a shop foreman at a Pete dealer and he said he had no idea, and didn't recall anyone ever coming in with a similar problem. However, he was happy to try and figure it out for $100/hr.

Has anyone here had a similar issue? Could my problem be around the area where all my wires go though the firewall and in to the cab (though I can't see anything visibly wrong)? Thanks for any help or suggestions. I am usually pretty good with wiring and finding things, but, this has me stumped.

 

My fuse panel light quit at the the same time also. At least I am not alone now. I haven't run my truck much in the last month so I have not messed with it, but, I think you motivated me to dive back in to it today to see if I can find the problem.

 

Thanks Longhood. You had posted that schematic for me before on tdg (at least I am pretty sure it was you). While it is a nice link to have, I was never able to make heads or tails of anything with it. All of my fuses are good, and have power to them. Now that you took the time to post that link to the schematic again, I am going to have a second look to see if I overlooked something.

 

Well, a little good news bad news. Longhood, per your suggestion to look at the one marked "roof", I indeed found a bad fuse. Wierd thing is it looked to be ok, but, for s's and g's I plugged a new one in it's place and I have working lights. For what ever reason I never focused on that particular fuse until today.
The bad news is that I had some of the lights on, walked to the pass side box to check that light and it didn't work, thought maybe bad bulb, no. When I walked back around I realized they were all out again, and the new fuse is blown. I guess now the search is on to find a short. At least having it narrowed down to 19 (thanks Longhood) will make it somewhat easier, I hope.

 

Yeah maybe check that you don't have a wire rubbing up there somewhere. When it's not raining that is the first place I am going to look to find a possible short. My truck has great clean wiring that has never been messed with, except that upper console where my stereo is. The former owners had all kind of stuff going on up there.