GM wiring??

Dick2

Well-known Member
Nephew tells me that his Mom's big Buick suddenly started draining the battery when it sits a couple days without being run.

Any ideas where he should look for the cause?
 
put a test light between your neg post and neg cable, if you have a short some where the light will light, Then pull one fuse at a time till the light goes out then you will have idea were to look for the short. Poor mans short tester.
 
I'm guessing that it's about a 1996 - 1998, whatever was Buick's largest model back then. Might even be a year or two newer?
 
Some Park Avenues have a weird battery cable setup that needs to be checked. My money is on the battery, hot weather is a killer on batteries. Not too much common on those. Check for stuck door lock switches and seat switches.
 
Poor mans? Actually it's one of the smartest and most efficient ways of finding a short if there is one.
 
Battery under the back seat? If so follow the ground cables to the tops of the rear shock towers. Unbolt the cables from the towers and clean up all the connections. Leave the battery disconnected for about an hour. If the body control module looses ground, it can do all sorts of weird things. If you have a scanner, it will not communicate with the bcm with a corroded ground.
 
First thing I would do is charge the battery and load test it.. then get the car started and check the alternator out put..all the electronics in the car make it tough to look for shorts with the old bulb between the negative battery post and ground. More than likely the battery is beyond it's replacement time.
 
Check battery first. I have replaced 3 batteries this year, car, truck and tractor. New battery solved the problem each time.

Same symptoms.
 
And check the radio,they will short out and stay on, with the fey off make sure the display is out.
 
Use an ammeter inline with the cable and battery post to find a parasitic draw. Just don't turn on the headlights and blow the fuse in the ammeter. As previous poster said pull fuses one at a time. The ammeter will show even a very small draw that test lights may not. Also charge and load test the battery. Turn everything on except the engine for 5 minutes. Voltage should not drop below 10 volts across the terminals.
 
On my GM it was the power trunk lock that wouldn't switch off and the little electric motor drained the battery. Another time it was the power antenna unit that kept draining the battery....not any more...they're both unhooked now.
 
Ideally a fully charged 12v battery will show 13.2 volts. Once started if the alternator is OK you should have about 14 volts, also check voltage with full electrical load (A/C, lights, radio, defrosters, etc, on) and you should still be over 13.2 volts.
 

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