Was driving the car yesterday, stopped for gas and it wouldnt start. Strong smell of sulfur from the battery. Jumped it and got it home. The battery was boiling. I removed it from the car. Trying to troubleshoot the short, I found a direct short to ground on the small wire that runs from the +batt terminal. After disconnecting the firewall connector from the fuse block, no short in that wire under the hood anywhere. Tried my ohm meter on the fuseblock itself: every circuit on the block is directly shorted to ground. Has to be somewhere on the under dash side of the batt+ circuit. (maybe a short in the fuse block itself). Anyone have this problem before or any ideas? Is this going to cost me a new harness or can it be fixed??? HELP!!!

Was driving the car yesterday, stopped for gas and it wouldnt start. Strong smell of sulfur from the battery. Jumped it and got it home. The battery was boiling. I removed it from the car.
You may want to check the charging system, boiling batterys are usually from overcharging. It may have boiled out all the fluid and killed the battery, which is why you needed a jump. The easy way to check the charging system is to check the voltage at the battery with the car running at a fast idle, should be 14-14.5 volts.

Trying to troubleshoot the short, I found a direct short to ground on the small wire that runs from the +batt terminal. After disconnecting the firewall connector from the fuse block, no short in that wire under the hood anywhere.
That small wire feeds everything in the car, was the wire burned?
http://www.chevelles.com/showroom/data/500/medium/Original_Chevy_system.jpg


Tried my ohm meter on the fuseblock itself: every circuit on the block is directly shorted to ground. Has to be somewhere on the under dash side of the batt+ circuit. (maybe a short in the fuse block itself). Anyone have this problem before or any ideas? Is this going to cost me a new harness or can it be fixed??? HELP!!!
That is really a invalid test. The all will show continuity to ground if anything on those circuits is turned on, and it only takes one item, like a open door for the dome light. For tracing shorts, use the test light method. If you don't find any burnt wires, you may not have a short. The charging system may have killed the battery.

Just to confirm, the battery is still ok, I hot wired the car and it started fine with the same battery (I still have the fuse block disconnected). I didnt know that one circuit on would show continuity on all circuits. Could you elaborate on the correct procedure for using a test light? When everything was still hooked up, the power wire to the headlight switch, ignition switch and fuse block continuity checked to ground, which makes sense as according to your diagram they are all connected at a splice. Do you know the physical location of the splice? (maybe something is shorting there). Also, I didn't mention that prior to this happening, my dash lights didnt work, when I turned on a turn signal, both indicator lamps would flash on the dash (the correct one brighter than the other) and if I turned the dimmer switch all the way up, both turn signal lights and the hi beam indicator light would come on. I just replaced the headlight switch in case there was a problem with that, but havent tried it yet as the fuse block is still disconnected.

68's are notorious for blinker and dash-light problems associated with poor grounds at the headlight switch, or at any of the dash bezel grounds (ignition switch, upper left corner of the plastic dash bezel). But those problems usually won't cause the symptoms you're having.

It's MUCH more likely you are just getting an overcharged battery as suggested before. The wire from the positive battery terminal, like the fuses, will show continuity with ground if anything is on (like a door is open). I'm not an electric expert, but I'd guess your voltage regulator or your alternator have gone bad. A Voltage regulator that can't regulate would be my guess... maybe the points have arc'd and formed a bridge (i.e the charging circuit is always on). If it were me (and this might be stupid... Elree Colby is the guy to ask), I'd take the alternator to Autozone or NAPA and have them test it. If it checks out, buy a cheap voltage regulator and see if that fixes your problem. Good luck.

Thanks to all for your input, still havent figured it out, I havent been able to check the charging voltage yet, I reconnected everything and got one start out of the battery, I shut it off to go get my voltmeter and after that it only will turn the engine over about a quarter of a revolution then just stops, battery voltage now showing 12.9v, which still should be enough to crank it over in my opinion. Turned on the lights with the new headlight switch installed, still having similar issues, the turn signal lights and the hi beam light come on at any setting of the dimmer now, although I found that if I played with the switch by just pushing the knob in slightly (not all the way to the off position), I got the dash lights on and the signal and hi beam lights went off. I know its not the switch, its brand new, I suspect theres some kind of short in the lighting circuit somewhere, also, when the parking / headlights are on, the fuel guage drops to anywhere between empty & a quarter tank. Could a bad ground cause all these problems?? I think I'll take it to an electrical shop later this week and see if they can locate the problem. I'll get the alternator and starter tested also.

I would say it is a ground problem in the dash probably in the headlight switch. Has the dash been out before? If so i would say that is your problem as far as the lights and gas gage are concerned.

You probably have more than one problem which makes it much more difficult to diagnose. Is the car completly stock or has it been modified (stuff like internal regulator alternator or alternator swap to passenger side)?

A true short will usually burn wires up. Melt insulation. Smoke. Smell. Stuff like that. If you lack any of those symptoms you probably do not have a short. If you do you will need to divide and conquer. Pull all the fuses from the panel to provide a degree of isolation. Leave all switches in the off position. Concentrate on the circuits/wiring upstream of the fuses. Contrary to prior information you really *can* troubleshoot a short with an ohm meter. You just have to use a bit of Ohm's law and some common sense. The trick is that resistance will not be infinite but some value, and to figure out what current would result from that value. Given a current you can do a "is that reasonable" test on it and decide. Nice thing about using an ohm meter is A) all power sources are disconnected/removed and B) ohm meters never burn up wires :-)

Presuming no short, you should start with the charging system checkout. The alternator can be removed from the car and tested stand-alone. If it is bad, replace it along with the regulator. If it is good you may still need to replace the regulator. You may be able to get the regulator tested stand-alone too...

Grounds can be very funny things. Have you noted any drop in head light brightness? If you lose a ground on a head light you can light up the HB indicator on low beam (it uses the high beam bulb filament and then wiring back to the indicator light as a ground path). There are gound wires on both sides to check, they may have been reworked in the past using substandard techniques and materials. Any time you see bright where expected associated with dim where you don't expect, think bad ground.

The ground of the headlight switch is not critical as it is not used for general lights, only for the turn-on of the dome light. You can also verify this ground with the wipers: if the wipers work this ground is functional (both switches share a ground).

The ground of the dash (really instrument cluster) as at least somewhat functional or your indicator lights would not work.

So get the charging circuit: alternator, regulator, and battery validated first. Then progress to further system troubleshooting.

Thanks for all your input. Got it back from the electrical shop all fixed. There were several issues, the diodes were bad in the alternator, which fried the battery, so got a new alternator with internal regulator and bypassed the old external regulator. New battery installed. There was a short at the brake light switch and a bad ground at the dash - all fixed and everything seems to be working ok for now.