73 battery drain, how to check out?

[el_guapo]

Alright, my 73 350 has a drain somewhere. I have hooked up a test light between the ground cable and post, no light turns on. However leave the car alone for a week and there isn't enough juice to crank.
The battery and alternator are both new. Thank you in advance guys
Anthony

[Corts60]

I had this happen to me on a '76 Nova I had. It turns out the horn button was stuck in the contact position in the steering wheel and since the horn was disconnected I couldn't find out what the hell was draining my battery. Then one day I decided to hook the horn up and it blasted my ears out and after I fixed the button, my battery never drained again.

Not saying that is your issue but it is one possibility. Good luck!

[el_guapo]

Hmm there is an aftermarket steering wheel. I'll do some reading, thank you for the tip.
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[travis401]

hook up a volt meter on the amp setting on the battery and see what amp load is on the battery with nothing on. you should only have a few miliamps of draw with the ign and lights off. if you see more than that start unplugging fuses until you see the amp load drop. that will narrow it down to a specific circuit and you can easily figure it out from there.

[grs]

Disconnect the neg battery post. If you see a small spark you have something using voltage. Undo the fuses one at a time. Then recheck by touching the cable to the battery. If you have a newer radio undo it during the test. I think that would help. You could have a bad battery also.

[Goldfinger]

also try to pull out fuses if you see sparks that one is drawing then trace the wires

[Cue-Ball]

The best way to diagnose this is to remove the negative cable from the battery. Then hook up an amp meter between the negative cable and the battery post. Make sure to close your doors so the dome light is off. If something is draining the battery the amp meter will show a draw. A stock '73 should have 0 amps draw since there's no radio memory or anything like that drawing all the time. If you have a fancy stereo, an alarm system, etc. you will have a small draw (those systems constantly draw amperage, but very little). Now it's just trial and error of pulling fuses and disconnecting stuff until the draw disappears. Once it does, you know your culprit.

[el_guapo]

great, thank you for the information guys. Any idea what setting to have on the multi-meter? I'm assuming I will be checking for current?
Thank you. Anthony

[john_p]

yes current.. if you pull the positive post, the red probe goes on the battery, the black will go to the battery cable you just removed..

[el_guapo]

Thank you, well wallmarts closed so I followed the advice of pulling fuses looking for a
Spark. No dice, however not sure what this thing is but the bastard was really warm.
It was connected dangling near the fuse box, any idea what it is and if it could be what's robbing the battery?

Posted via Mobile Device

[grs]

Originally Posted by el_guapo

Thank you, well wallmarts closed so I followed the advice of pulling fuses looking for a
Spark. No dice, however not sure what this thing is but the bastard was really warm.
It was connected dangling near the fuse box, any idea what it is and if it could be what's robbing the battery?

Posted via Mobile Device

Check your horn, turn, and flashers with the relay disconnected. Find out what the relay is for. Something won't work with it disconnected. Try to trace where the wires go.

[Palf70Step]

Originally Posted by el_guapo

Thank you, well wallmarts closed so I followed the advice of pulling fuses looking for a
Spark. No dice, however not sure what this thing is but the bastard was really warm.
It was connected dangling near the fuse box, any idea what it is and if it could be what's robbing the battery?

Posted via Mobile Device

That looks like the horn relay and from the way you described it hanging there, I am thinking that is what it is.

Like the others mentioned, Hook a meter up. You can also check the connections where that relay goes to see which ones are hot. I believe the wide one is the hot (Orange wire). One of the lower two (Dk Green) goes to the horns. The other one (brown) is to the horn button. At least these are the colors on mine. If I remember right, orange and brown should be hot. Green dead unless the horn button is depressed. (These were colors on my 83, they may be different on yours.)

Thos relays are notorious for failing or shorting.

[Goldfinger]

looks like a relay, chances are the short isn't going into the cab

[el_guapo]

I see, I think I'm going to have a pro check it out. I don't mind turning a wrench or body work. But electrical is a little overwhelming. I was thinking what I would do if I found where the short was. Haha, thank you everyone for the help!
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[Goldfinger]

Usually i'm good at finding shorts because they seem to wanna catch fire

[76Blue_Beast]

Yeah I know the feeling Goldfinger! My 76 had a short and the fire department found it while I was at work. Now I have to replace the harness. If anyone needs harnesses go to American Auto Wire. They were cheap but quality for the older vehicles and custom work too! Very helpful people and they have some helpful techs that can walk you through your questions.

[72lb4x4]

If you took one battery terminal off, put a light between the battery and the removed terminal, and got no light, you have no current, or the current is too small to light the light.

Now you need to measure with an ammeter, or figure out why your battery is dead.

Maybe the battery is old, and won't hold a charge, isn't charged long enough, or your wiring is messed up.

Get a charger, charge the battery for a few days, measure the battery voltage with the engine off and running, etc.

[Goldfinger]

gotta love the smell of melting wires

[el_guapo]

Battery is new, my guess is becoming the wiring. I will figure this thing out. I'm in it cheap for how nice it is. I'll get it
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[Goldfinger]

Goodluck finding it and as i've learned in the past if it become a more noticeable draw you should carry a fire extinguisher.

[el_guapo]

With some reading I found it is a horn relay. Can I simply leave the relay unplugged to turn the horn off?
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[grs]

Originally Posted by el_guapo

With some reading I found it is a horn relay. Can I simply leave the relay unplugged to turn the horn off?
Posted via Mobile Device

Unplug it and see if the horn works or not. Then find out where the bad wire is. Don't drive around without a horn.

[Goldfinger]

Originally Posted by grs

Unplug it and see if the horn works or not. Then find out where the bad wire is. Don't drive around without a horn.

x2 on that