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Old 07-12-2018, 04:54 PM   #1
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Location: Corvallis, OR
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Parasitic battery drain

I'm working on a 1999 Suburban and the battery keeps going dead. In two days it went from 12.5 volts to 11.6 volts. The battery is 1 year old and this started a few months back.

Are there any common parts or failures that cause this? I'll be diagnosing it this evening by connecting an amp meter between the battery cable to verify it has a significant drain (more than 50-100 mA), then pulling fuses one-by-one to find the circuit.

1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205
1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears
1996 Chevy Suburban K1500 350/4L60E
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Old 07-12-2018, 10:47 PM   #2
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Re: Parasitic battery drain

I'd disconnect the alternator, check current, reconnect, then disconnect the harness at the firewall, check current.
Ammeter, not amp meter...
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Old 07-12-2018, 11:00 PM   #3
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Location: North AL
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Re: Parasitic battery drain

For me one time it was my cargo light switch was on but bulb was I didnt never catch it but later traced it down to that.....also my buddy had a glove box light that would never turn off took a while to find it also he happened to see light through the crack one night when he looking for something on the floor.....
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Old 07-13-2018, 04:37 AM   #4
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Re: Parasitic battery drain

If you replace some of your interior lights with LED bulbs you will discover that there is so little current drain on those circuits that if left on overnight you won't have a dead battery in the morning.
1989 K1500 Chev. EC
Original owner; some of the aftermarket parts I've installed are Borla headers, Hypertech chip, Edelbrock water pump, and a Stillen rear disc brake conversion kit.
2009 Hummer H3T 3.7L 5M.
1997 K2500 Chev. EC 7.4L/ 4L80E
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Old 07-13-2018, 10:58 AM   #5
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Re: Parasitic battery drain

Check any power option that doesn't work. Power seat motors, window motors, & courtesy lights are common offenders.
89CCDually-Driver/Tow Truck
99CCSWB Driver
All Fleetsides

Building a small, high rpm engine
with the perfect bore, stroke and rod ratio is very impressive...
like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.

Cubic inches is like Indiana Jones with a cheap pistol....
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