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Hello all, I am new to this forum and wondered If I could tap on some expertise dealing with my granddaughter's car. She has a 2003 Malibu with a parasitic draw pulling the battery down within a couple days. With a bit of troubleshooting I was able to narrow the key-off drain to the BFC BATT Fuse F 10 A. The fuse lease to the of the one of the Battery Positive Voltage lines to the BCM. So far I am at a loss as to where to go from here. The BCM has two Battery Positive Voltage inputs. one from the BFC fuse and one from the LNT LPS fuse A also a 10a fuse. Any help you could offer would be greatly appreciated. Battery is new.
 

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The BCM is always drawing power to some degree. It runs a small current to keep certain features "alive", such as CTD (content theft deterrent). A small draw is expected.

A battery can also have an internal issue. How old is it, and has it been tested?

How much current are you seeing on any of those circuits?

One way to measure a parasitic draw is to put an ammeter between the battery and one battery cable after the key has been turned off. Any KEY OFF current will register on the meter because it is forced through the gauge.
 

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Thanks for your response. The battery was replaced. I traced the draw to the BFC fuse with by measuring the amperage draw. This fuse feeds the BCM Battery Positive Voltage. I checked all fuse for draw under hood, and left and right IP fuse boxes. This seems to be the only fuse effected. I am trying to determine what the Battery Positive Voltage is used for in this case. According to the BCM schematic, there are tow Battery Positive lines; however, this is the only one that has the excessive draw. I first detected the draw at the under hood fuse box from a 30 amp fuse labeled BEC Batt2 Fuse 3 accounting for the needed delay for the system to relax. Once relaxed I found the draw mentioned above. From there I checked all fuses and the only fuse with the continuous draw was the BFC BATT Fuse F 10 amp seeding the BCM. Any ideas of where to go from here?

I might add that the BEC batt2 fuse also showed addition draw for a while until the circuits relaxed. The BFC BATT Fuse F only shows the continuous draw. The anti theft system is working fine. Does the Battery Positive Voltage power the Antitheft or does it just enable another power source to fee the anti theft system?
 

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considerable battery current draw while the car is sleeping is over 200~250 ma depends on the car electronics and security system actually i didn't measure it while the car is healthy i measured only while troubleshooting. the best way to troubleshoot such type of faults is to hook up your ammeter and start to disconnect the loads to capture the moment when the ampere dropped in some cases you shall cut/desolder some wires.
hint: when you park the car do you see all the lights off in instrument cluster, gear lever position indicators, air bags ac control module) u can see that in darkness from outside the car also the gearbox lever should rest firmly in the park position.
 

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Thanks. This was helpfully. It seems I am down to shooting wires. I check the instrument lights and they all work perfectly. That'said what makes this a challenge. Their does not seem to be any other symptoms; however, the ignition key tumbler is worn. I have a replacement on hand including a new pass lock sensor. I will start buy replacing these and go from there. Thank you for your help.
 

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I have exactly the same problem with my son’s 2003 Malibu. Fuse f on the left side is causing a .09 amps continuously and eventually drains the battery in two days. Any ideas? Thanks a lot
 

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I have exactly the same problem with my son’s 2003 Malibu. Fuse f on the left side is causing a .09 amps continuously and eventually drains the battery in two days. Any ideas? Thanks a lot
Since I don't drive the car that often, I installed a switch under the dash to turn on and off the fuse circuit.
 

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Since I don't drive the car that often, I installed a switch under the dash to turn on and off the fuse circuit.
Excellent idea! What kind of switch and where'd you buy it?
I want to do the same for the exact same reason, my daughter doesn't drive it but once a week.
Did you run into any issues installing it?
 

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Excellent idea! What kind of switch and where'd you buy it?
I want to do the same for the exact same reason, my daughter doesn't drive it but once a week.
Did you run into any issues installing it?
It was the cheapest 10 amp switch at O'Reilly auto parts. You simply have to snip the orange wire to the BCM fuse and wire in the switch. In the 2002 it's the slightly smaller of two orange wires, but it's easy to find whatever wire with an ohm meter. As shown in photos I used a couple of blue wire nuts and zip ties to tie in to the orange fuse wire, they then screw on to the switch. I also used a piece of stiff plastic I found in the garage to extend the switch under the dash and then screwed the plastic to the dash. The extender might not be necessary with a switch with a longer grip which could be installed directly to the dash. The install was about an hour.

The switch and screws are actually not easy to see when entering or sitting in the car.

Good luck!
 

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It was the cheapest 10 amp switch at O'Reilly auto parts. You simply have to snip the orange wire to the BCM fuse and wire in the switch. In the 2002 it's the slightly smaller of two orange wires, but it's easy to find whatever wire with an ohm meter. As shown in photos I used a couple of blue wire nuts and zip ties to tie in to the orange fuse wire, they then screw on to the switch. I also used a piece of stiff plastic I found in the garage to extend the switch under the dash and then screwed the plastic to the dash. The extender might not be necessary with a switch with a longer grip which could be installed directly to the dash. The install was about an hour.

The switch and screws are actually not easy to see when entering or sitting in the car.

Good luck!
Bless you for providing this assistance. For grins my son and I tried to find the issue and for a moment we thought we had in the wiring of an aftermarket stereo. I was simply moving around some wires that I had disconnected while my son was watching the meter and it went from .11 down to .03
So, I start to tidy up the wires and darned if it didn't jump back to .11
I tinkered for at least an hour trying to recreate that brief glorious moment; but, to no avail.
I'll be going by OR's for that switch later today.
 
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