The Stovebolt Site Forums The Shop Area The Electrical Bay help?

i have a 68 gmc 3/4 ton where i just rpaced the starter ,regulator and alt is ok but system is still draining battery after putting back the way it came out i am replacing coil tommoroww i am grounded just off the bolt of the starter where in the wiring system do you think i'm losing juice i've put the battery charger on it several times only to see it drain an hour later thanks for your help

It could be a bad battery.

With everything turned off, pull a battery cable off the battery, and connect a DC volt meter between the battery and the cable. If you get a reading you have something using power. If you don't have a meter a cheap test light might do the trick.

With everything turned off the meter should read zero. If it reads zero I suspect your battery.

If it reads above zero start pulling fuses one at a time and checking the meter. If it goes to zero when you pull a fuse, the circuit related to that fuse in the problem.

You have a short and they can be tough to find. The brake light switch might be sticking. Check all your lights to see if they are on when they should'nt be. Try to do it in the dark as it might only be glowing a little bit. Dont forget the dome light if you have one. If not a light you might try crawling all under to look for any worn spots. Underneath is a good place to start but you should look under the dash and the hood. Any bare spot that can touch metal even a little bit will cause you trouble. I am not great with wiring but it is probably something simple if you can just look in the right spot. Good luck.

Take the cable off of the battery to charge it. If it is a good battery and it is discharged, it will take all day to charge it or even all night depending on the charge rate. If the battery is drained down and yet charges back up, in less than say two hours, it is probably bad.
If the battery is good and drains down in one hour you have to be getting one hell of a spark when you put the cable on the battery.
Do not put a volt meter between the battery and the cable. A volt meter is used for checking voltage and is not used to complete the circuit. It will tell you battery voltage if there is any drain of any size and little else. A current meter(amp meter) is placed in the circuit and will complete the circuit.
The light idea is a better idea. I use a single filament backup/park/tail light bulb with two wire leads soldered to it with a alligator clip on one lead. A little tape wrapped around the glass at its widest, keeps me from braking it every 5 minutes. When you are laying on your back under a dash , it is easier to see a light out of the corner of your eye than having to turn your head to read a meter.
If the battery is good and you have the test light between the bat and cable, you just have to lift your head up to see if the light is still on as you pull fuses. If no success with the fuses, try taking the bat connection off the alt. They can charge OK and still have a short that will discharge the bat with the motor off.
Actually, a fully charged battery with a one hour drain time would call for a trouble shooting technique that involved looking for smoke.

And that would be exactly why I suggested he do it. To determine if there is a drain of any size...

I've seen examples where a meter would show the drain, but it was too small to light a lamp.