electric draw making me crazy
Thread Starter
Melting Slicks
Joined: Aug 2013
Posts: 2,180
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From: S Fla
electric draw making me crazy
My 02 developed a "short" grounding out issue 2 weeks ago..started by battery not holding charge after putting on charger. this is not my daily so I keep a battery tender on it..tender was very warm and red light was still on after 5 days.. changed batteries and when new one was hooked up heard some clicking sounds up by headlights when the cables were being attached. took the Fluke meter and ran continuity check, sure enough an a open circuit...switched to dc and had a -12.5 draw. started removing relays it both under hood and behind foot well still had continuity...removed all the fuses under the hood and nothing broke the circuit. removed as many fuses behind the foot well until my back started to cramp up... took out all the 15 plus fuses again still beeping...Has anyone else had this issue and what might be the cause???. Thanks
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Il would check the battery tender. It sounds like
it has failed.
Good luck
it has failed.
Good luck
Melting Slicks
Joined: Sep 2008
Posts: 3,138
Likes: 802
From: Espanola New Mexico
The only way to measure current draw when the car is shut off is by placing multimeter selected to DC current and positive lead plugged into 10 amp jack, disconnect negative battery cable and connect meter in series with battery terminal and negative battery cable, should read 25ma after 15 minutes, this is normal sleep mode current draw. Perform this test and let us know what your current drain is.
Thread Starter
Melting Slicks
Joined: Aug 2013
Posts: 2,180
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From: S Fla
Thanks mmartinez: I had the meter's black lead connected to the neg cable and the red lead connected to the neg lug. That's how I found the -12.5 volts. I will give this test a try Friday morning..will keep you posted thanks again!
Drifting
Joined: Mar 2015
Posts: 1,421
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From: CSRA, SC
Yep doesn't sound like you're taking your measurement correctly. Not much that can pull a constant 12.5A and is suspiciously identical to the typical 12.5V battery voltage... let us know what you find.
Last edited by oharal; Dec 9, 2020 at 08:31 PM. Reason: spelling
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When it comes to testing draw, you should be testing amperage, not voltage. On the voltmeter below you should be using mmA setting and also having the leads in the proper holes, in this case, the middle two. Most meters have a max of 10 amps.
Like mmartinez said, wait at least 15 minutes for the car to go into sleep mode.
It's not unusual for certain pieces of these C5s to draw excessive amperage when they go bad. Two of the top ones are the power seat modules and the Bose amplifier.
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I once had a BCM go bad while I had the car stored in the garage for the Winter. I also had a battery tender connected at that time. It sat like that for at least 4 or 5 weeks. Tenders don't put out enough amps to keep a battery charged fully when there's a large enough draw on the system. Don’t get me wrong, tenders are a very good product. However, my draw was of sufficient amperage that my battery would be completely dead in 12 hours. It stayed dead long enough, with the tender trying to keep it charged, that it ruined my tender. A bad BCM may also be the problem you're having. I hope not. Good luck....
Intermediate
Joined: Sep 2004
Posts: 49
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From: Moline Il
One common problem with unknown battery drainage is; the drivers seat adjustment switch. I had this problem too so as test I unbolted the seat to get access to the bottom and disconnected the harness.
That solved my problem. Be sure to adjust the seat to your liking before you do this.
That solved my problem. Be sure to adjust the seat to your liking before you do this.
Thread Starter
Melting Slicks
Joined: Aug 2013
Posts: 2,180
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From: S Fla
I want to thank everyone for their help ...Found out the battery had a bad cell...changed it out and I did the test as suggested, (The tender is still good battery couldn't hold a charge). After checking the system and then waiting 20 min and checking it again the car was shut down no draw. I didn't realize the 02 had a sleep mode, feel like a bonehead. but the Vette started right up very strong this morning. No hesitation or slow cranking. Thanks again for all your suggestions and advise. Bill