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Tracing down an electrical draw?

y5mgisi

y5mgisi

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Ok so, I never had a problem with my battery being dead in my '78. I could let it sit for 2 or 3 weeks and go out and start it right up. That was untill i found out my blinkers werent working and hooked up the conector at the bottow of the stearing coulomn that controls the blinkers, horn, etc. Now my battery dies within a couple days. So dead it wont even make an attempt to start. So how do i trace down the draw? I have a DMM. Should i disconect one of the battery cables and place my DMM leads between the battery and cable, then start pulling stuff apart untill i get a 0.00 reading on the DMM? if so what setting would i use?:confused:
 
i'd diconnect one of the battery lugs and put a test light in between the battery and the cable, and start pulling fuses watching the light to see if it gets dimmer or not, then atleast u know what circuit its in, there will usually always be some draw due to the radio etc.. though
 
Use your amp setting, The high one just in case the draw is high amp. If you put your leads between the battery and conector you should read and amp draw. If it is small enough, you can move your leads to the mA side. Then start pulling things off till 0.0 mA. DO NOT turn anything on that pulles any power or you'll blow the internal fues in the DMM. Not the end of the world just replace it but a PITA:doah:. Repair what you find and reinstall the cable.
 
If you've got a Radio Pull that fues first and don't forget about the dome light if the doors open. Chased that a while.
 
You've made sure that your alternator is charging properly? Made that mistake myself when my battery wasn't staying charged very long. :)
 
Ok thanks for all the tips so far. My hunch actually is that it ghas something to do with the horn circut. And my radio is the factory one with no electronic memorie that im aware of(true push button presets). And the charge guage says about 14 once its fired up. My dome lites dont work but i will keep that in mind as a possible draw. And thanks for the run down on how to use my DMM for this as i broke my test light recently.
 
set the DMM to milliamps. the number you want is less than 30 milliamp draw. With the setup you describe it may even be less.. Set the DMM between the neg cable and post and do as others described about pulling one fuse at a time. Fast guess is an internal short in the turn signal switch. The wiring going up the column is pretty small gauge.
 
Interesting. I did not know the alt could do that. Thanks again for the tips! Going to check it out tomorrow.
 
If you find a problem with the horn circut, be aware that there are a ton of items on that circut, the horn, dome light, cigarette lighter, the relay for the fuel tank selector if you have dual tanks (found that one out when I ran out of gas with half a tank left), and possibly the brake lights (someone correct me if I'm wrong). hope you get it figured out.
 
Ok so i ended up not getting to diagnose much yestersay but i did figure out that the draw is originating from the steering column. The only way i could end up getting my DMM to work is with it on the 10A setting and it was drawing 0.48A with the connector at the column hooked up and 0.00 with it un hooked.
 
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