dash panel lights not working...

First off...whole car (66 Skylark) was rewired with all new harnesses in 2017, so nothing is hacked.

Dash panel lights were working until recently.

I've got aftermarket gauge lights tapped into the panel lights circuit in the fuse box using a fuse tap that has a male spade terminal sticking out that I connected the aftermarket gauge lights to with a female spade connector. The fuse panel glass fuse is good for the dash panel circuit. The dash panel circuit is completely dead, no power. Checked with headlights on, key on, engine off, headlight switch knob turned from all the way dim to all the way bright, to dome light on positions and all the different combinations. The circuit is just dead, no power at the fuse box. Headlights work fine. This is still the original headlight switch.

Is it possible the headlight switch is bad?

I tested the aftermarket gauge lights by supplying power to them using a different circuit, so I know the aftermarket lights work.

Any other ideas? I do have a new ACdelco switch on the way. I've already removed the old switch from the dash, just wondering if there's anything else I could check. I do remember the switch acting kind of funny(not working like it should) a while ago but I don't remember exactly what it was doing. Then it went back to working normal again and I didn't think much of it.

So...headlight switch?

Thanks.

 

Just by pass the switch and see if the lights light up?

I am thinking it's not the switch. Just guessing of course. Sometimes the circuit board on the back of the dash panel gets wonky... Another guess.

I would test the switch, and try bringing power to the lights, then you know if the lights light up, and if the switch is bad.

 

I thought the dashboard lights and the parking lights front and rear were connected to the same fuse. If true, you don’t have any back lights either.

 

https://www.teambuick.com/reference/library/66_chassis/files/66_special_wiring.php

According to this wiring diagram(Thanks Teambuick! I do have the factory service manual at home, btw)...it looks like power goes in to the headlight switch, comes out (dk. green) in to fuse panel and then out (gray) to the instrument lights.

Since I'm getting no power at all to the fuse panel, I'm thinking it could be the switch. Unless I'm reading the diagram wrong.

I appreciate the responses. I will try to do the suggestions later this evening.

 

Headlight switch should be getting power since the headlights actually turn on and off and I can turn the knob(dimmer) all the way to turn the dome lights on and off. It's just the panel illumination lights that won't turn on.

 

Here is a youtube video with the pinouts of the switch and it should help you test.

 

Ha! Forgot I do have a power probe. Just haven't used it yet. I'll try that later this evening.

 

I've forgotten more than I remember but I think Waterboy is correct. I remember no dash lights = no tail lights, I believe it was a bad ground on the tail lights that was causing the problem. I've owned lots of cars and I'm not sure it was a Buick I was working on. Like I said I've forgotten more than I remember lol.

 

I do see a brown wire on the schematic that goes from terminal 4 of the headlight switch, through the body harness and back to the taillights. The instrument panel lights go through terminal 2 of the switch to the fuse panel. I never checked if the taillights were on when the headlights were on, but thats another thing to look at later. Either way, it all goes through the headlight switch. I'll power probe both wires and see what happens.

Thanks.

edit...that's a pretty good video.

 

Ok...plugged switch back in and checked if taillights were coming on with the headlights. They were not. I unplugged the switch and using the PowerProbe, I applied power to the dk. green wire(panel lights circuit) and the panel lights lit up. I then applied power to the brown wire(taillights) and the taillights lit up. So, I don't think it's a ground issue. I'm thinking headlight switch. New one is on its way, should be here tomorrow or Fri.

Thanks to all for the help.

 

Ok...success...finally.

The new headlight switch didn't fix it...yet.

After installing it and finding out I still had the same problem, I went back to the schematics and the video shown above.

Looking at the wiring diagram, got me thinking about why the guy in the video was jumpering #1 and #5 pins with 12v. Looking at the diagram, there is a 12v red wire going to my fuse box labelled tail feed, dome, and clock. Coming out of that fuse, the wire goes out and then splits to the clock and glove compartment light, and over to pin #5 on the headlight switch. So that is where #5 gets it's power.

So, I go back to the fuse box with a multimeter. Switch is plugged in, battery hooked up and key is in the on position. I checked every fuse under power(which I hadn't done, except for the circuit I was having issues with. Turns out I had 2 fuses that didn't have power coming out. The panel fuse and the fuse that #5 pin in the headlight switch gets it's power from. It's the very short 10A fuse. Apparently, the panel light fuse gets it's power through the #5 headlight switch pin.

Changed that fuse and got my instrument panel lights back. I had been overlooking that fuse because it said dome light, but my car has sail panel lights instead of a dome light above on the roof. I had been thinking that since my "dome" lights were working, I never checked that fuse.

So, thank you Max Damage for posting that video. It helped a lot. It was the main reason for eventually finding the answer.

Even if it wasn't the switches fault, it had been acting flaky, so it needed changing anyway.

I was going nuts trying to figure out what the heck was going on. Not as bad as Jason and the Ford alternator nuts, but still annoying.

Sorry for the long post, but I hope it helps somebody else who may have the same issue.