Lights out... and gauges too

[Armo67]

I've been working on my 67, trying to clean up the wiring mess from the PO. When I got the truck, the lights worked but the gauges and gauge lights did not. Now none of the lights work and the gauges and gauge lights still do not work. Could this be caused by a headlight switch going out?

I've checked and it's all getting power and all of the fuses are good. I've tested all of the glass fuses under the dash and they are all showing good, except for the one in the lower right hand corner, There is no power on either side of this fuse, With the light switch knob in any position. I'll try and get a pic of it, I believe it's labeled PNL LIGHTS, which would explain the gauge lights not working I guess.

I've also switched the 4A fuses in the engine compartment to blade fuses because one of the old glass ones was blown and the other was blown, crushed and disconnected.

[Armo67]

ok, I went back out and popped fuses out, cleaned the connections, popped them back in, and now the lights work. still unsure why they would have stopped working and started working again in the space of a day or two.

It looks like the gauge lights still aren't working, but the turn/hazard arrows are working. The headlights are working, but when I hit the dimmer switch, the lights go out.

also, between the 4 brake lights, I have working tail lights, brake lights, blinkers and hazards.

so if anyone has some input on the headlights and gauge lights I'd be interested to hear it.

[Fitz]

Originally Posted by Armo67

ok, I went back out and popped fuses out, cleaned the connections, popped them back in, and now the lights work. still unsure why they would have stopped working and started working again in the space of a day or two.

It looks like the gauge lights still aren't working, but the turn/hazard arrows are working. The headlights are working, but when I hit the dimmer switch, the lights go out.

also, between the 4 brake lights, I have working tail lights, brake lights, blinkers and hazards.

so if anyone has some input on the headlights and gauge lights I'd be interested to hear it.

When the dimmer switch begins to go bad, for whatever reason, problems come up with the rest of the lights. I had the same problem with my 67. Changing the dimmer ($10.00 at autozone) got the lights to settle down enough to droubleshoot the rest. These old trucks used plated brass for the terminals in the fusebox, so the act of pulling the fuses rubs the corrosion off the terminals allowing them to make good contact. My fuse panel is in the pic; and you are correct, the lower right fuse labeled PNL is the fuse for the dash lights.

[GASoline71]

Just like Fitz described... Same for me in the 1967 C10 I had eons ago... dimmer switch was the culprit.

Gary

[Armo67]

Thanks a lot for the responses guys! I'll be swinging by and picking up a new dimmer today or tomorrow, whenever time allows.

Hopefully that will fix the headlight issue. Not sure it will do anything for the PNL fuse not getting any juice. I've tried scraping the fuse holder though, that didn't seem to make a difference on that fuse. (helped with others).

[Armo67]

After looking at the image that Fritz posted, it looked a little different than the one in my C30 so I cleaned up mine the best I could for a pic. More of the lettering is there than I thought, there was just a lot of dirt and grease on it. It doesn't look like the fuse I'm asking about is labeled PNL at all. but labeled LTS, it was just so covered with junk I couldn't see it. posted a pic below.

What exactly does the PNL go to, and should something be plugged into it? (Out of curiosity)

I'm assuming LTS stands for lights, as that is the abbreviation for them, but not sure which ones. perhaps the gauge lights? since those are not working.

I've been trying to search the site for a breakdown of the fuse box and what it all goes to and does. haven't found one yet, but still looking.

[Dova]

I had a problem with one for the wipers that the contact rusted enough that it wouldn't work. Hopefully all the contacts are making good connection and you don't have that problem.

[Bigdav160]

That's a crusty fuse box. Plenty of electrical resistance there.

I'm pretty sure the light fuse is powered after the switch. So it won't show any power with the lights off.

[Fitz]

Originally Posted by Armo67

After looking at the image that Fritz posted, it looked a little different than the one in my C30 so I cleaned up mine the best I could for a pic. More of the lettering is there than I thought, there was just a lot of dirt and grease on it. It doesn't look like the fuse I'm asking about is labeled PNL at all. but labeled LTS, it was just so covered with junk I couldn't see it. posted a pic below.

What exactly does the PNL go to, and should something be plugged into it? (Out of curiosity)

I'm assuming LTS stands for lights, as that is the abbreviation for them, but not sure which ones. perhaps the gauge lights? since those are not working.

I've been trying to search the site for a breakdown of the fuse box and what it all goes to and does. haven't found one yet, but still looking.

You need to get a factory assembly manual. It covers 1967 through 1972 C, K, blazer and all flavors of GMC.

My 67 C-10 has a different fuse panel than your K. Attached is the diagram that goes with your panel. The fuse you say is marked "PNL" is actually marked "PNL LTS" or Panel Lights. Since the panel is removable, the pigtail supplying power to the panel lights is plugged into your panel in the spot adjacent to that fuse. See the attached diagram from the factory manual.

[Armo67]

Fitz, thanks again for the help. I've picked up an assembly manual and it is helping a lot. my 67 isn't a k but it is a c30 so that is probably where the difference in fuse panels is coming from.

I stopped today at lunch and picked up a new dimmer switch and installed it. hi-beams are now working! so now the only thing left to figure out is the gauge lights.

[tarafied1]

Originally Posted by Armo67

Fitz, thanks again for the help. I've picked up an assembly manual and it is helping a lot. my 67 isn't a k but it is a c30 so that is probably where the difference in fuse panels is coming from.

I stopped today at lunch and picked up a new dimmer switch and installed it. hi-beams are now working! so now the only thing left to figure out is the gauge lights.

Any luck getting your instrument lights working?
I found this thread searching for help on the same issue. My 72 is having the same problem

[tarafied1]

After posting above, I went out to look at my fuse panel some more. Only one of my turn signal indicator lights in the cluster was working so I took it out and moved it to different locations in the cluster (after replacing the bulbs in all of them with no success). That one worked in each location so I figured the bulb holders (plastic thing) must be bad on my truck. I dug through my boxes of old parts and found a few, swapped them out and now I have instrument lights! The old ones don't look bad but must be corroded I guess.

[Armo67]

Haven't gotten them fixed yet, but haven't had a whole lot of time to work on the truck here lately. I plan on spending some time on it this weekend. will post with what I come up with.

[Sammy]

Not sure but believe wire color coding remains the same on all like year trucks. Fuse locations might be different but should use same colors. If you get power thru the PNL fuse I would suspect a crappy panel circuit on your dash panel. From the looks of the condition of your fuse box I would re clean all your grounds before you get too involved.
Don't forget what is posted here. http://67-72chevytrucks.com/vboard/s...d.php?t=185856