Possiblly a bad bcm?
11-20-2011, 01:54 PM
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Possiblly a bad bcm? Heys guys I have a 97 ss and I have been trying to find out why my battery keeps dying. I checked for parasitic loss with a multimeter and this is what I got. When I hooked the meter up and checked the amps I had 0.04 amps. Started pulling fuses to see if it would drop a little and it didn't. What I found was that when I open a door I get a reading of about 2.25 amps which is normal cause the door is open. Now I closed the door and watched the meter and the interior lights at the same time. When I first closed the door the meter said the same 2.25 amps. As the interior lights went dim the amps dropped which I understand. When the lights were off I was getting a reading of 0.10 amps now. If I unhooked the meter and then reattached the amps went back to 0.04? Something is telling me the bcm is draining the battery from my results. Also as soon as I hook up the meter to the battery and positive terminal I here the bcm in the car click. Anyone got a clue if I'm on the right track thanks
11-20-2011, 04:23 PM
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Gotta find out what other accessories are powered by the BCM. Something else could be draining through the BCM.
Page 10
http://cs.chevroletclub.net/graphics...g.diagrams.pdf
Gonna have to unplug stuff until the draw stops and trace it back. Wonder if the ignition key could be sticking.
Page 10
http://cs.chevroletclub.net/graphics...g.diagrams.pdf
Gonna have to unplug stuff until the draw stops and trace it back. Wonder if the ignition key could be sticking.
11-20-2011, 04:39 PM
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Only thing the fuse says is bcm its very general lol. I don't think its the ignition sticking cause the only response from the meter I get is when the interior lights are supposed to go on. Thanks for the link btw
11-20-2011, 07:07 PM
#5
It's completely normal for the BCM to draw more current for several minutes after the last door is closed. Then, as part of the "battery saver" circuit, the BCM "goes to sleep". Anyone who has installed an aftermarket alarm has experienced this "going to sleep" function because it has to be bypassed to make the alarm work properly. So your readings of .1 amp after closing the doors followed by .04 amp when the BCM is asleep seems quite normal.
11-21-2011, 07:51 AM
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Its an aftermarket radio but its not draining the battery I've disconnected it and the battery still dies. I know about the bcm going to sleep but I only get that .04 if I disconnect the probes then reattach. If I leave the probes hooked up it stays at .10
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11-22-2011, 11:48 AM
#8
I'm wondering if your use of the meter is itself keeping the BCM awake. Have you tried leaving the probes disconnected for at least 15 minutes after closing the doors and then attaching them to check current draw? My thought is that the BCM remains awake when you have the probes attached until you remove and reconnect them so it might be useful to test if the .1 amp draw occurs when you don't start with the probes attached.
11-22-2011, 06:24 PM
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The .10 draw only occurs after the door is opened then closed. If I hook up the leads after the door is closed its at .04 maybe I'm not letting the bcm fully go to sleep and I'm assuming its staying at .10 the whole time. I think I'm going to recheck. Also just noticed that if I first hook up the probes to the battery and I have my .04 reading, in I pull the fuse for the air pump the amps drop to .02. The only things that are on that circuit are the air pump (which has been deleted) and the cooling fans. Could that have anything to do with it?
