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Discussion Starter · #1 ·
My Blue 98 GMC Safari had a parasitic drain for 2 months & then went away
--I checked all fuses, removed all accessory bulbs, never found it
--Only after market item is an alarm installed by others

My Grey 97 Chevy Astro just had a 2 week parasitic drain & then went away
--Only checked fuse block in engine compartment, didn't find it
--No after market anything that I know of

Batteries are both new

I have read many articles about tracking parasitic drains and watched a few vids, it's all the same

Does anyone have any ideas what makes it 'cure itself'?

TIA

Bill
 

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1998 LS AWD Forest Green metallic
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My only 'guess' would be the lamp in the center console drawer, occasionally being left on, by a warped drawer not pushing the switch properly. It is a fairly common issue, that many have encountered.
Rod J
 

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Mine turned out to be the alternator. It would charge fine while it was running, but would then drain the battery when it sat. I replaced it when I did the engine swap, it's been fine since.
 

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Always nice when things fix themselves, right? (Except that leaves one with that unsettling feeling the problem will come back at the worst possible time.)
You didn't say how long it took for the parasitic draw to run down the battery. Overnight or over the course of days?
I've seen where people use a meter with an amp clamp to measure how much of a load occurs when everything should be off. (There will always be some draw just to hold computer and radio memory.) If I recall, they measure at battery cables first, then move on to branches.
If you suspect a circuit then pull the fuse to it. Depending on results troubleshoot that circuit or move on to something else.
Nice thing is 97 and 98 is pretty old technology compared to the can of worms you might encounter today.
Hopefully it was just the storage compartment light as Rod's Trucks suggested.
By the way, noticed the Oldsmobile logo for your picture. Learned to drive LONG ago in an Olds and still have occasional dreams about that '53 88 2 door hardtop. Had several Oldsmobiles in my life, still have one today. Another favorite was my 1988 Touring Sedan.
 

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2004 Safari RWD, 2002 Astro AWD
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Another internal item that you may look into is the timer circuit that turns off the radio after a few minutes before opening the door to get out.
I am not sure if it is separate circuit or part of a body control computer box.
Also check and see if any USB adapters are left plugged in. Some of them drain a tremendous amount of power when supposedly doing nothing.
All fine when engine is running but end up draining the battery quickly over time. Especially if the van is used only once or twice a week.
 

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Discussion Starter · #6 ·
Always nice when things fix themselves, right? (Except that leaves one with that unsettling feeling the problem will come back at the worst possible time.)
You didn't say how long it took for the parasitic draw to run down the battery. Overnight or over the course of days?
I've seen where people use a meter with an amp clamp to measure how much of a load occurs when everything should be off. (There will always be some draw just to hold computer and radio memory.) If I recall, they measure at battery cables first, then move on to branches.
If you suspect a circuit then pull the fuse to it. Depending on results troubleshoot that circuit or move on to something else.
Nice thing is 97 and 98 is pretty old technology compared to the can of worms you might encounter today.
Hopefully it was just the storage compartment light as Rod's Trucks suggested.
By the way, noticed the Oldsmobile logo for your picture. Learned to drive LONG ago in an Olds and still have occasional dreams about that '53 88 2 door hardtop. Had several Oldsmobiles in my life, still have one today. Another favorite was my 1988 Touring Sedan.

Thanks for the help

Battery of blue truck discharged much slower but can't quantify

Battery of Grey truck discharges very fast, you can take voltage readings 3 mins apart and watch it go down

My father was an Olds guy, my grandfather was a Pontiac guy. I'm both but then there was the Austin Healey & the BMWs
 

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1998 LS AWD Forest Green metallic
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BillyJoBob,
Start with the 'grey' truck. It should be much easier to figure out if you have any test equipment.
You can even use a small 12v test lamp. Put in series with a battery lead, for significant drains. If the lamp lights up, start pulling fuses and or disconnecting circuits until you find the problem. ( you might have to disconnect the alternator if that is cause). When you find where the load is, the lamp will go out. Then start tracing parts of that circuit.
An accurate wiring diagram will be helpful, if you can follow it.

Then move on to the Blue truck after gaining some experience on the grey one. If it is a small draw, and the test lamp does not light up to help you, try putting an analog volt meter ( one with a moving needle instead of a digital one) in place of the test lamp. A digital volt meter is much too sensitive for this type of test, and you will likely go nuts looking at the digital display jumping all over the place. Clamp-on ammeters are nice, but expensive ( be careful-many do not work on DC circuits), and often will not show small drains.
You can increase the effective minimal measurement capability of a clamp-on amp probe buy using a small wire wound into a coil of ten turns or so. Tape the coil so the clamp-on probe can grab around all ten coils, and hook the leads of the coil in series with the battery cable ( or other circuit you are tryng to test). That ten turn coil the probe is clamped around will result in a ten times increase in the displayed result.
Rod J
 

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Discussion Starter · #8 ·
Thanks for all that, Rod

If neither truck is discharging now, no battery drain, will this test still tell me where the drain is?
 

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NO, if there is no current drawn from the battery, these tests will not help you.
To prove if the test actually works, experiment when you are not having a problem. Connect the small 12v lamp in series with a battery cable. If your interior lamps are working as they should, just opening the door will be plenty of a load to light the test lamp. Most any small load ( not sure about the radio memory circuit, so it might not register) should illuminate a small 12v lamp in series with the battery lead. You can use either battery cable for most issues.
Rod J
 
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