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Discussion Starter · #1 ·
Hi all, looking for some suggestions. I have a draw somewhere in the electrical system and hooked up my meter inline and see a small draw on the battery. I was able to narrow down the draw to the interior lights by pulling that fuse and seeing the draw drop to zero.

I can visibly see there are no lights on and am looking for suggestions where to look. I've disconnected the service light under the hood and with all doors closed can see no interior lights on.

Any ideas where to look next ?

Thanks
 

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By pulling that fuse did it disable anything other than those interior lights? Did all the lights work before? Could there be a short? Could it be in the headlight switch rheostat/dimmer for the dash lamps. Just throwing out guess's here, not sure how your's is equipped.

Any draw in the exterior lights?

95% of the electrical draws that I personally have had to deal with pertained to aftermarket radio & the way they were hooked up.

Bucky
 

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the door interior light switch , screws into the sheetmetal , if you can unplug the wire from it from behind , or unscrew it and unplug the wire , it is the same as having the door closed , because that wire is "looking" for a ground . unplug it . Now with your meter ( or a test light ) between the - post of the battery and the disconnected - battery cable , remove 1 fuse at a time , and watch the "draw" if the light goes out ( draw drops to 0 ) when a fuse is removed then you have "found" the circut that has the draw . some things are NOT fused by the fuse pannel , and some have a "normal" small draw . The clock and presets ( memory)on your radio for example will draw a small amount all the time . While the 4 ways or a shorted diode in the alternator should not be lighting a test light ... how much is this draw?
 

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Not much on that circuit. 2 door switches, the lite on the dash, and its switch. The hatch switch, and a diode in the line with the cargo lamp, so it only comes on with the hatch switch, or the dash/ headlamp switch. And the light bulbs.

And of course all the wiring in between.



I would start by hooking the meter up again, put the fuse back in place, Then wiggle all the switches, and look for a change.

Then continue by removing the two bulbs, since they are the easiest. if one of them stops the current draw, look at the switches between the light and ground. If the craw is still there, then you can narrow the search to the wiring between the battery, and the bulb. Remember, the bulbs have power all the time, and are turned on by switching the ground side.
 

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Discussion Starter · #5 ·
712edf said:
By pulling that fuse did it disable anything other than those interior lights? Did all the lights work before? Could there be a short? Could it be in the headlight switch rheostat/dimmer for the dash lamps. Just throwing out guess's here, not sure how your's is equipped.

Any draw in the exterior lights?

95% of the electrical draws that I personally have had to deal with pertained to aftermarket radio & the way they were hooked up.

Bucky
Thanks for the tips. Nothing besides interior lights were disabled when I pulled the fuse that I was able to see. Headlight switch/dimmer is new, I suspected an issue with it a while back and replaced it just to be safe.

What I did was to setup my meter with long leads on the windshield so I could see the readout from inside. Closed all the doors to see all lights were off, then proceeded to pull the fuses one at a time until the meter dropped to zero.

When you say issues with aftermarket stereo, what issues did you find ? I did recently install a new Pioneer head unit and this may have started afterwards. Hard to say since this is still work in progress and it sits alot.
 

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Darinm said:
Thanks for the tips. Nothing besides interior lights were disabled when I pulled the fuse that I was able to see. Headlight switch/dimmer is new, I suspected an issue with it a while back and replaced it just to be safe.

What I did was to setup my meter with long leads on the windshield so I could see the readout from inside. Closed all the doors to see all lights were off, then proceeded to pull the fuses one at a time until the meter dropped to zero.

When you say issues with aftermarket stereo, what issues did you find ? I did recently install a new Pioneer head unit and this may have started afterwards. Hard to say since this is still work in progress and it sits alot.
If your draw is significant, you might have reversed the always-hot wire for the key-switched hot wire. (the always-hot is supposed to be a low-draw circuit to preserve your radio station presets and clock)
 

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Discussion Starter · #7 ·
Confirmed that radio always on and switched are correct. Radio will shut off with ignition and still keeps it's memory and clock. I suppose a test could be to disconnect radio with VOM meter connected in series for amp draw and see if it goes away.
 

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My radio issues were radio would work at ALL times, plus on one of them they had an amplifier that wouldn't turn off. This was back in my younger days when I thought I had to have a loud system. Today I usually yank out any audio components within a week of buying my old beaters.

Bucky
 

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radios have 2 leads that require power (D/C+ ) one needs to be connected to battery , the other needs to be connected to a keyed power ( key on = power on ) Radio should NOT play with key OFF . now the battery power one WILL cause a meter to show a draw all the time BUT it should be a very low amount , so low that a good car battery will stay charged enough to start the auto for months even with that draw . When you get into large high powered amps , they should be run thru a battery disconnect switch . There are 2 types of those , manual operated , and key operated , both should sized to be able to handle the full amperage of the battery/s used .  my question to the original post , how much draw does it have ?  if its high ,  one place to check is the alternator , a shorted diode can cause a draw  , disco the main lead to the alt and retest .

you can set a radio to work with the key off , but then its on you to be sure the radio is switched off when your not using it ... lol
 

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Darinm said:
Confirmed that radio always on and switched are correct. Radio will shut off with ignition and still keeps it's memory and clock. I suppose a test could be to disconnect radio with VOM meter connected in series for amp draw and see if it goes away.
It will still do that with the two hots flipped. I made that mistake when I put a 90s factory radio in my 75. Put the meter back in line w/ the bat and unplug the stereo.
 

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I don't want to send you down rabbit holes, but on a couple of occasions I have had batteries with a dead/defective cell give similar symptoms as to your's. You could charge the battery to full charge & it would work fine to crank the vehicle. But if you left it hooked up for any length of time (sometimes even with the engine running), it would soon go dead. It would hold the charge much longer with a cable disconnected. Actually this seems to apply to healthy batteries too.

Back in the days of pre-computers, our 77 LTDll had such a bad battery. I would start the car, disconnect the positive cable (and insulate the end of it), then drive it on the alternator. Things got tricky at red lights or at night haha. Of course we can't do that with out new & improved vehicles. Progress they say.

I don't think this is your issue (based on your fuse pulling tests)... but something to look into if all else fails.

Bucky
 

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Discussion Starter · #12 ·
712edf said:
I don't want to send you down rabbit holes, but on a couple of occasions I have had batteries with a dead/defective cell give similar symptoms as to your's. You could charge the battery to full charge & it would work fine to crank the vehicle. But if you left it hooked up for any length of time (sometimes even with the engine running), it would soon go dead. It would hold the charge much longer with a cable disconnected. Actually this seems to apply to healthy batteries too.

Back in the days of pre-computers, our 77 LTDll had such a bad battery. I would start the car, disconnect the positive cable (and insulate the end of it), then drive it on the alternator. Things got tricky at red lights or at night haha. Of course we can't do that with out new & improved vehicles. Progress they say.

I don't think this is your issue (based on your fuse pulling tests)... but something to look into if all else fails.

Bucky
Thanks Bucky, in fact I did suspect the battery and since it was 5 years old based on the sticker, I went ahead and replaced it since it didnt have too long left on it.
 
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