97 oldsmobile cutlass supreme dieing battery?
battery tester December 28th, 2008this cars battery is being drained by something, i checked all the fuses, alternator, interior lights, all the major things. i can still tell it is draining the battery because of a light tester.
any ideas? thanks
yes i pulled the fuses nothing
Your battery is most likely being drained by your alternator. A bad resistor/diode on an alternator will cause it to drain slowly…usually overnight. I doubt you have another item draining power, if you did you would've probably noticed some other symptoms.
I would recommend taking the vehicle to a local auto parts store and let them run a diagnostic on the charging system. This is a completely free service and will report any dead cells in the battery, how much drain is being put on the battery, whether the diodes in the alternator are functiong properly, etc.
With 13 years of experience and 7 owning a shop I can pretty much guarantee the alternator is the culprit. If you don't feel like taking it up for a free charging system diagnostic simply disconnect the alternator while your light tester is plugged in. You should see the difference right away.
Hope this helps!
December 28th, 2008 at 12:08 pm
Using the light tester like you were,start unplugging fuses one at a time until the drain shows up.Don't be fooled by the interior light circuit in the process.
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December 28th, 2008 at 12:57 pm
On General Motors cars, it is possible to have the alternator fail in such a way that it will pass any testing, but it will be the device that is draining your battery.
This is very difficult to diagnose at the alternator tests good, but is really the problem. Even experienced mechanics miss this one.
Replace the alternator.
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December 28th, 2008 at 1:09 pm
Your battery is most likely being drained by your alternator. A bad resistor/diode on an alternator will cause it to drain slowly…usually overnight. I doubt you have another item draining power, if you did you would've probably noticed some other symptoms.
I would recommend taking the vehicle to a local auto parts store and let them run a diagnostic on the charging system. This is a completely free service and will report any dead cells in the battery, how much drain is being put on the battery, whether the diodes in the alternator are functiong properly, etc.
With 13 years of experience and 7 owning a shop I can pretty much guarantee the alternator is the culprit. If you don't feel like taking it up for a free charging system diagnostic simply disconnect the alternator while your light tester is plugged in. You should see the difference right away.
Hope this helps!
References :
After Hours Automotive - (User Owned Restoration Shop)
December 28th, 2008 at 1:29 pm
It sounds to me like you have invested a lot of time into this problem. I would have started at the interior lights, specifically the door switches themselves. My Mom's cutlass had the same problem which my brother and I overlooked. A lot of times those switches short out on the back side and drain the battery overnight. If your door switches are all good then the next place to check is the grounding wires that ground the engine to the chassis. Make sure they aren't overly corroded. Make sure your ecm is grounded properly because they are a constant draw on your battery. The only other things I can think of if is your glovebox light and your trunk light. Make sure they off when you park the car. You'd be surprised at how easy it is to leave them on. Good luck.
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