Puzzling Electical Problem

[Born Lucky]

O.K. here is the situation.
I drove my C20 1964 292 engine for the first time in the night. Everything was fine for about 10 miles then my dash light when out. I still had my headlights so I thought I was O.K.
The next day I start looking at the problem and come to find out I also had no rear lights, but my turn signals work. So first thing I look at the fuse panel and I find a blown fuse. Now, I change the fuse and everything works.
Here is the puzzling part! If I idle everything is fine but the moment I drive off the fuse blows. The fuse blows when I have my headlights on.
I guess I have electrical issues. I really hate finding shorts!!!

[neto]

Just so that you know we are looking at your question that's why I'm posting a response. I have no idea what it could be. The only help or advise is to post the same question in the electrical area. They are really good figuring things out.

[TheDark1]

I once had a step side bed with loose tail light brackets, that would do the same thing. The tail lights were grounded through the brackets. Only the headlights would work when the fuse would blow. I would look for a bad ground somewhere first, then a cut or damaged wire on the hot side. I hope this helps. Jeff

[61_FL_Apache]

Look at your headlight switch. All lights seem to be connected there.

[65Guy]

All the power for headlights, tail lights and brake lights come threw the head light switch so after many years they cant carry all that current. Best bet is change that puppy out less that a 20 spot ant LMC.

[Bugeyev8]

my 62 did the same thing 2 times, each was related to the taillight harness, the first time was a wire that the coating had fallen off of the wires to the R tail light asy, 2nd time it was a wire at the firewall connector for the rear harness ..same thing with the coating falling off the wire, these trucks are wired so simple, its very easy to find the issues, the only issue will be after some monkey gets under the dash with a roll of electric tape and wire cutters and "re wires" the truck, my 62 was bought new by my grandpa in 1962...its had ony 2 electrical issues since new and I now am running a TPI efi engine since 1995 and no issues

[70inline6]

Originally Posted by Born Lucky

... If I idle everything is fine but the moment I drive off the fuse blows. The fuse blows when I have my headlights on. I guess I have electrical issues....

Just a thought... in what condition is your voltage regulator? I suspect the light switch as well, but if the switch checks out, and you can find no dead-shorted wires... I'd check the VR.

[Born Lucky]

Well after looking at the shop manuel I come to think that it might be the headlight switch or the voltage regulator( Napa counter person suggested this). My regulator is orginal to the truck so it is old.
Well I am off to the garage to touble shoot. FUN!
Thank you all

[raycow]

Try this test first. Unplug the alternator connector. Now start the engine and do whatever you did that caused the fuse to blow before. If the fuse doesn't blow, plug the connector back in and drive it some more. This will tell you if the problem is voltage-related or is caused by vibration shorting a wire somewhere.

Ray

[Born Lucky]

O.K. elecrical problems are so f*****ing strange.
I tried removing the headlight switch but I did not have the tool for the bezel ( anyone known what to use) then I started looking at wiring that the PO had sliced , taped etc..
Started the truck went for a ride and viola no problems.
Hey guys what is the different between the $20.00 voltage regulator and the $90.00 one. I known one is period correct, but I do not care for that.

[DPowers]

Don't know about the VR, but as far as the bezel is concerned, I have used pliers with the jaws taped up or the end of needle nose pliers into the slots.

[Born Lucky]

Originally Posted by DPowers

Don't know about the VR, but as far as the bezel is concerned, I have used pliers with the jaws taped up or the end of needle nose pliers into the slots.

Now do you turn the bezel like you would a bolt, screw!

[aerotruk63]

When you want to remove the headlight switch,what has worked for me, press on the mushroom pin which will unlock the pull. You might have to try pushing on the pin a few times while moving the pull in and out. Once the pull has been removed twist the switch counter clockwise while holding the bezel with the tip of your fingers. if you get some loose between the switch and the bezel, rotate the assembly clock wise then hold the bezel and rotate the switch counter clockwise once again. two or three times doing this and you should be able to twist the bezel off with your fingers.

Worst scenario a tap with a punch and hammer counter clockwise,should knock the bezel loose then you can do the rest with your fingers.

[l79m20]

Sounds like the old dimmer switch problem, check connections and or rust out. new ones are cheap fix...................just my 2 cents

[fixit-p]

Your problem is in the wiring after the fuse.

The fuse is fed by the headlight switch not the other way around (fuse does not supply headlight switch).
edit>>>>WRONG I was thinking the dash lights fuse is after switch the stop/tail fuse is before, my bad but the diagnosis is the same<<<<

So if the fuse blows the short has to be on the load side of the fuse. Possibly in the cab (because the problem seemed to go away after you moved wires around under the dash (intermittent short)).

[lakeroadster]

Originally Posted by l79m20

Sounds like the old dimmer switch problem, check connections and or rust out. new ones are cheap fix...................just my 2 cents

x2

[Born Lucky]

Originally Posted by fixit-p

Your problem is in the wiring after the fuse.

The fuse is fed by the headlight switch not the other way around (fuse does not supply headlight switch).

So if the fuse blows the short has to be on the load side of the fuse. Possibly in the cab (because the problem seemed to go away after you moved wires around under the dash (intermittent short)).

I will look into that next time I have a chance.
Right now everything seems to be fine. I did a little troubleshooting and all seems well. But we all know those elecrical problems as they seem to manifest when you lease want them to.