Question about 1994 GMC Suburban

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Battery goes dead if left connected over night. Is it because of the voltage regulator? Also, is the regulator built into the alternator?

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No, the regulator really has nothing to do with anything that could discharge the battery when the ignition is off. The only way that's possible is if one of the diodes in the regulator was shorted, and if that was the case, the battery would never get charged.

And yes, it's bolted right onto the alternator.

Finding the cause of a current leak like that is a PITA. I usually start by hooking up an ammeter inline with the battery (ignition turned OFF!) and pulling fuses out of the fuse block one by one. When the amperage draw drops significantly, I know I found the fuse that operates the circuit that's draining my battery.

If none of the fuses do it, then there's something else connected before the fuse box that's doing it. Usually that means a poorly installed stereo, subwoofer amp, or alarm system.

If you can't find it that way, then you have to get a copy of the electrical diagram and eliminate one circuit at a time until you find the bad one. It's not terribly hard, but it is time consuming and you have to be proficient at reading schematics.

If that sounds too hard, an automotive electrical specialist shop is your best bet. Take it to the specialist, not the joe blow mechanic shop down the street. You'll pay more per hour than a general mechanic shop, but they'll fix it, correctly, in half the number of hours. I can tell you from experience in the field that many many excellent mechanics are still intimidated by electrical problems.

Posted on Dec 31, 2010

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Replace the Negative cable to your battery. I have had this problem before. try that and let me know how it turns out

Posted on Jan 25, 2011

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