Electrical glitch

[uberbeans]

Hey. This is my first thread to this forum but in the past I have found lots of useful information. I was wondering if there was any advice concerning an electrical problem. I have a 1980 Blazer (home built 383, Detroit locked 12 in the rear, ARB in the front, sm465/205, etc. to much to list) that I replaced the body on. There isn't on bolt on it that I haven't wrenched on. I reused the old body's harness on the new chassis. The truck runs great except for one thing, if it sits for three or more days, the battery loses it charge. I suspect a constant draw somewhere. It has a 140 amp alternator (new), and a Optima red top (new), good grounds between the body, frame, engine, battery to body, battery to frame, alternator bracket to the body. I had the charging system tested and everything is working great, including the battery. If I start it up everyday it doesn't lose enough charge to be a problem, but after about three it needs a jump. The stereo has a constant charge to keep the memory but this shouldn't be enough to drain it for a month. Any ideas on troubleshooting? ANY info would be appreciated. This is not a new problem, just something I have been dealing with since the truck was rebuilt. I runs GREAT, charges GREAT, just doesn't hold the charge. Thanks in advance.

 

[diesel4me]

Find your shorts...

You likely have a short or something draining power--take off one battery cable and hook up a test light between the battery post and the cable--if it lights up,something is sucking juice from the battery(a clock in the dash might show as a draw,or make the bulb flash once in a while--pull the fuse out for the instrument cluster)--you will have to pull the fuses one at a time and see if the light goes off--if it does,the draw is in the curcuit that fuse protects,so check the wiring to whatever that fuse is protecting..

..if the light stays on no matter what fuse is pulled,then something that gets constant power is drawing the juice--bad diodes in the altenator,shorts in the main power wires from the solenoid to the fuse box,headlight switch etc--you have to take the big red wire off the altenator and see if the light goes out--if it does its the diode trio in the altenator "leaking" current to ground(be careful the red wire doesnt touch ground,its "hot" all the time an will fry!!)

-I had one truck that the wiper motor never shut off completely and killed the battery--the strange thing was it worked normally,and the blades did not attempt to keep "wiping"--but the motor was warm to the touch on a cold day when I went to investigate for shorts--changed it,and the battery has stayed up since!--electrical gremlins can suck...-good luck!

 

[uberbeans]

Thanks for the quick reply! I have tried the test light trick and I know that there is a draw. I know the stereo is a draw. The test light works kinda weird: it has an initial glow then it dies down. If you do it immediatly again it doesn't glow as much the next time. If you wait 20 seconds or so it builds up again and glows bright, then dies off gradually. I thought that perhaps it was the stereo only because it seems that it is a capacitor because it takes a while to build up the need for the draw. I hope this makes sense. The stereo by itself shouldn't be enough to draw down the battery so quickly. The truck is very simple the only extra wiring is the electric fuel pump (holley with a painless wiring relay), the electric brake control for the trailer, It has new wiper motors (from lmc) , new horn, new alternator. Thanks again.

 

[dyeager535]

The best thing to do is with a test light (if it works in your case) or a voltmeter, test for draw as you have been with the light.

Then, start pulling fuses out of the panel until the draw disappears. If you check all fuses, then you'll have to start checking things that have been added and are seperately fused or unfused. The door locks and windows I *believe* are both on circuit breakers instead of fuses as a for instance.

 

[uberbeans]

Thanks, I'll try this out.

 

[diesel4me]

unsolved mysteries...

While testing one of my trucks for a short I noticed the test light acting goofy like you described--I finally got it to go out when I unplugged the big pink wire on the HEI distributor!--I checked my other 2 trucks that had no battery drain problems--they lit the lamp up the same way!--I still cant figure it out,why there is juice there,when the ignition is "off" it should be dead!--but its not!--it must be a very slight drain, the batteries dont go dead,so I'm not losing any sleep over it--it is strange though!!..

 

[uberbeans]

So, on the first truch when you disconnected the pink wire it made the light stop the "illuminate, then fade" problem. What is the pink wire? Does your truck run without it connected?

 

[diesel4me]

HEI power wire ..

The big thick pink wire that goes into the distrubutor cap was the one that I pulled and the light went out--truck wont start with it unpluggd,no juice to distributor==no spark,no start!...I never have figured out why there is evidenly some power at that wire with the key "off",its not 12v as it is dim,but it doesent drain the battery,so I just chalked it up to another of lifes unsolved mysteries...