Re:2007 chevy suburban...bcm fuse parasitic draw

2007 chevy suburban, 5.3l vin 3, 1500 4x4. New napa battery. I have verified that the amp draw of 2.0 amps is at the bcm fuse located in the IP left fuse box on the dash. This started killing the battery over night about a month ago. With this fuse removed within say 20 seconds the draw goes down to less than 20ma and can set for days and be fine.
Here is what I have discovered so far through my troubleshooting. Cycle key on and off, remove key, shut door, and within a couple minutes everything dies down to less than 20ma.
Here is the problem. Just like a timer at the ten minute mark, I hear the gauges wake up, no lights, gauges return to resting after 10 seconds or so but I get a steady 1 8 - 2.2 amp draw until the battery dies. I can repeat this over and over. I have subscribed to Mitchell's and have been using the prints to try to figure this out. Any help would be greatly appreciated. I am getting burned out on troubleshooting. Thanks in advance.
If this has been solved before please point me in the right direction. I couldn't locate a thread on this exact problem anywhere., Bill

Any signs of water intrusion near BCM or corrosion in BCM connector?

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Everything appears to look good in the area of the bcm. No signs of water in or around the floorboard area underneath. It is my feeling that the vehicle was garage kept. Also the milage is 150k. There are no signs of anyone being in this area before. I have unplugged the 7 connectors from the side of the bcm, checked for anything odd visually and reseated. I was able to repeat the issue after doing this. Key on, key off, close door, and everything goes to sleep. At almost exactly 10 minutes the gauges awake and the 2 amp draw continues until you either cycle the key or the battery dies. Your help is very appreciated!

Draw is large enough to find with an amp clamp or clamp meter which makes things easier if you have one. You could separate the power feed wire from the harness and check it first to confirm the draw is flowing into the BCM. It's possible something else might also be on that feed. That'll give you a BCM or something else direction.

If it's going into the BCM then you could clamp the other wires, a bunch at a time, to see where it's leaving the BCM. When you find the draw then split that bunch in half then keep dividing until you find the individual wire. Then use wiring diagram to find what's on the wire.

Great ideas!! Thank you Matt!

I did the first part of your suggestion Matt. I found the bcm fuse wire on plug c-3 wire location pin 3 on the connector. There was no current on the isolated wire at the bcm connector. So I check all 7 connectors at the bcm and none of the connectors have any current on them. I start back tracking from the bcm to the I/p left fuse box where the bcm 10 amp fuse is located.
I pull the fuse box out where I can get to it and there is no current on any of the 3 connectors on the front. There is no current on the wires on the main connection on the back. Im really scratcging my head at this point.
All the while I'm verifying my 2 amp draw at the under hood fuse box. I was able to get my amp clamp on the bundle of wires as they enter the firewall from the outside fuse box and have the 2 amp draw there.
It got dark on me so I am now searching the prints to see what all is on the LBEC2 fuse in the underhood fuse box that powers the bcm fuse inside.
I guess the only question I have at this time is why do I not have any current draw at the ip fuse box where the bcm fuse is located, but when I pull that fuse the current draw goes away? Will post more tomorrow. Thanj you

Bc25241 wrote: I guess the only question I have at this time is why do I not have any current draw at the ip fuse box where the bcm fuse is located, but when I pull that fuse the current draw goes away?

Because the fuse may be feeding the BCM which in turn is telling something with a 2 amp current draw to switch on.
Go into live data in the BCM and check the inputs to see if there is anything 'different'.
I once had a Porsche that was keeping 5 modules awake and draining the battery - it turned out to be a broken switch in the glovebox.
Because it thought the glovebox was open and as soon as it saw a door open it switched on all the modules that a person sitting in the car
might need to activate [seat motors etc.].

Ok. I think I understand? The pcm may be using milli amps to command something on but the actual current is coming to whatever that may be from somewhere else. Thanks

Matt T wrote: you could clamp the other wires, a bunch at a time, to see where it's leaving the BCM. When you find the draw then split that bunch in half then keep dividing until you find the individual wire. Then use wiring diagram to find what's on the wire.

That is a great tip, and a real time saver. Be aware, though, that if you have the culprit, current-flowing power wire and its ground both in the clamp, they will cancel each other out and you will not see it on the scope.

Chad, is this also true with an amp clamp?

Yes that is true of an amp clamp or any other style of inductive pickup

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Bc25241 wrote: Ok. I think I understand? The pcm may be using milli amps to command something on but the actual current is coming to whatever that may be from somewhere else. Thanks

Yes - on the vehicles I have had issues with removing 5 different fuses could take away all the current draw, leaving out the one for the BCM would
prevent it from returning - but when the BCM has power it can command the other modules via CANBUS to wake up.
One fault I had was a VW Golf drawing current, even though the display turned off with ignition off it had a communication fault code, it couldn't
receive its command to fully shut down via CANBUS. The radio had to be replaced.

How many connectors does the bcm have? If you have unplug one bulkhead connector at a time the one with the issue should take the draw away. Then you’ve narrowed it down

Cheryl wrote: How many connectors does the bcm have? If you have unplug one bulkhead connector at a time the one with the issue should take the draw away. Then you’ve narrowed it down

All that does is add more variables to the equation. Doing that could cause a variety of issues with other modules in the system.

I have slowly removed all of the inside covers throughout the week. I have done this to be able to unplug connectors one at a time. I would unplug something, cycle key on and off, wait ten minutes for the timed draw to show up and repeat. Last night at dark I unplugged a pyle branded rear seat monitor and was finally able to not see the 2 amp draw at the ten minute mark. If the battery is still up this morning i might have found it. I will check later and report back.