No Brake or Dash Lights

['68 Short Step]

everything has been working fine until a few days ago when my taillights and dash light quit working. I looked at the fuse and it was blown. Replaced the fuse and everything worked again. about 5 miles down the road the taillights and dash light quit working again. Checked the fuse and this time nothing was blown. I replaced the headlight switch and dimmer switch because they looked old and corroded. Still nothing. any advice on best place to check wiring would help. Everything seems to be connected. thanks for the info

[bobs409]

Did you do any work just prior to this happening?

The reason I ask is I once had the back bumper off my stepside and when I put it back on, I pinched a wire in there and never noticed. I stopped at a traffic light and smoke started coming out of the column when the brakes were applied! (wish my fuse HAD blown, it melted some turn signal switch wires that were NOT fun repairing)

I'd start by inspecting your wires to see if there is anything pinched or shorting out.

[DKclassis72]

do anything to your steering column? I pinched some of the wire going down the column and that caused the same issue your dealing with.

['68 Short Step]

Well I installed my vintage air system and cleaned up the wires under the hood by wrapping them all up but everything looks connected. Took the dash cluster off and all wires look ok.
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[FLDBRED]

Is your dash cluster grounded?

['68 Short Step]

I will double check the dash today and make sure its all grounded. Does it normally ground on the metal part of the dash?

[tr69c10]

Check you turn signal springs inside the column some times they can short out when they touch the column it happened to me
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[VetteVet]

Your tail light power originates at the fuse panel where the red wire from the battery harness connects and feeds the stop/turn/tail fuse. From there an orange wire branches out and feeds the headlight switch, the brake light switch, and the dome light. It also feeds the green wire on the headlight switch which runs through the dash light variable resistor and back to the fuse panel to the PNL LTS fuse, where a gray wire runs to the dash cluster to feed the panel lights.

When you blew the stop/turn/tail fuse you lost those functions. when you replaced the fuse it restored the brakes and turn lights. What I suspect happened is that the brown wire which runs from the headlight switch shorted at some point in the circuit and opened the tail light circuit which accounts for not blowing the fuse again.

The tail lights are powered by a brown wire from the headlight switch, which runs through the connector in the firewall behind the distributor, and down the firewall along the frame with the turn/brake and backup light wires. Check along that harness and at the tail lights for a break in the wiring.

Here's a picture diagram of the harness. The fuse panel is in the lower right corner and the panel lights wire is marked by the arrow. The orange wires are shown also.



Here's a diagram of the headlight switch wiring from the fuse panel.



here's the tailight and dome harness.

['68 Short Step]

Thank you very much for the details. I will check everything out when I get home later. All of the advise is very much appreciated. It's frustrating that I finished my vintage air system and can't enjoy it because of the electrical issue.
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[Duelly]

Had the same kind of problem. We got caught in a heavy down pour and was 60 miles from home and all my tail lights, marker lights and dash lights all blew 2 different fuses. Had a friend follow me home and checked it out the next morning on a beautiful sunny morning and 2 fuses were blown and the fuse box was wet and the terminals were kind of rusty. The truck has been parked in a storage unit until this weekend when I plan to get it out and try to find the problem. Some say that the windshield may have to come off. This was new last September when I bought the truck. Its a 1970 Chevy CST/10. Don't dare go to far until the leak is fixed. From some of the pictures that I have seen it could be rusted through the bottom of the windshield. and the new windshield would have to come out and checked for holes. I have never done anything like this so, I will have to have a glass repair shop take a look at it. We will see what happens.

[Rich72C10]

I seem to have gotten a gremlin but not sure when it popped up with my work on the truck. This morning (still dark) I discovered parking/running lights, break lights, dash lights, and dome like did not work. I found my "Tail Stop Park Dome" fuse was blown and replaced it. Figured I did something naughty in the last week and did not notice it (since I been test driving in daylight).

A bit later this morning (daylight now) I did my test drive that I needed to do after replacing the fuel pump to carburetor hardline (still no leaks there YAY) but when I pulled in the garage my dome light wasn't coming on (and the other lights of course). Again my "Tail Stop Park Dome" fuse was blown. Ugh!

Replace the fuse again. This time I tried to go through areas I remember mucking around wiggling various wires/harnesses to see if I could get it to blow. Nope. I did two test drives following the same path that forced me to do the same braking/turning/etc. Still didn't blow the fuse. After returning to the garage I did the same wiggling around areas again while in the garage, fuse is holding.

I am bouncing between under the dash (driver side) since I did pull speaker wire across to that side. Then popping to the engine bay and wiggling wires around the battery/passenger headlight. Since there I pulled the battery and tray to replace the LED lamp and fuel vapor canister.

So my question (its safe to assume I introduced this short) is there anything common to this fused orange power run around the battery/passenger headlight and the harness that goes across the radiator? Well, other than actual battery power... I didn't seen any orange being pulled over there.

PS: the biggest suck here is that I lose my breaking lights - that is a big downer. So during my test driving/drives I am keeping my dome light on!

[Rich72C10]

Okay, can now make "Tail Stop Park Dome" fuse blow on demand.

It is when the left turn signal is on and when I apply the break... whatever that means or where. Perhaps something pinched around the battery tray/passenger side. I know I didn't do any work on the break lights.

I think it is time to self flagellate for causing this.