Battery drain

[Michigan]

I’ve been through hell with my 2004 Tahoe z71 it’s a long story but I’ll try to keep it as short as I can. It does not have automatic hvac controls

Years ago I had a remote start and touchscreen radio put in by a reputable audio shop and I think that’s where my issues began but not sure

I needed up having all that taken out but that shop

It’s ate up about 4 batteries including a yellow top and red top optima and has cost me thousands in repairs at different shops to no avail.

Latest was last week the last shop said I was drawing more milliamp from my instrument cluster so that was fixed and once again put a new battery in it but the battery will read 12.3 volts the next day so I called that shop and they assured me there were no more draws

So I asked them if I the audio shop had not removed everything like interface if it would cause a draw and he said yeah it’s possible as he did not specialize in audio

So I took it back to that audio shop and they didn’t find any draws but said that I should have a voltage drop test on the whole circuit. he said that my alternator is putting out 13 volts. I called the last shop and told them what the audio shop said and he said that something would show up on the dash?

This car is not a daily driver. Any ideas why the battery is losing voltage overnight?

 

[Sackett2622]

I have had the same random battery drain over the past two years, did the same things, alternator tested, new battery, etc. I finally figured out that the BCM ( Body Control Module) which is supposed to sleep when the vehicle is off, is not going to sleep all the way..due to it “thinks” that my stereo is still on. In order to fix this, you can have the BCM replaced, or you can take it to a shop to have the old one re-flashed, or you can unhook both battery cables from the battery, leave them off overnight. Next morning, put them back on and this will teach the BCM to go to sleep when it is supposed to. A re-flash here in my area is about 200.00 so I would try the battery route and see if it resets the BCM first. Good luck .

 

[Fless]

Start with a parasitic draw test to see what the draw is after your cluster was fixed.

 

[Michigan]

I have had the same random battery drain over the past two years, did the same things, alternator tested, new battery, etc. I finally figured out that the BCM ( Body Control Module) which is supposed to sleep when the vehicle is off, is not going to sleep all the way..due to it “thinks” that my stereo is still on. In order to fix this, you can have the BCM replaced, or you can take it to a shop to have the old one re-flashed, or you can unhook both battery cables from the battery, leave them off overnight. Next morning, put them back on and this will teach the BCM to go to sleep when it is supposed to. A re-flash here in my area is about 200.00 so I would try the battery route and see if it resets the BCM first. Good luck .

Thanks for the tip. Disconnected both terminals a couple hours ago. Also

I have had the same random battery drain over the past two years, did the same things, alternator tested, new battery, etc. I finally figured out that the BCM ( Body Control Module) which is supposed to sleep when the vehicle is off, is not going to sleep all the way..due to it “thinks” that my stereo is still on. In order to fix this, you can have the BCM replaced, or you can take it to a shop to have the old one re-flashed, or you can unhook both battery cables from the battery, leave them off overnight. Next morning, put them back on and this will teach the BCM to go to sleep when it is supposed to. A re-flash here in my area is about 200.00 so I would try the battery route and see if it resets the BCM first. Good luck .

Thanks for the tip. I disconnected both negative/positive a couple hours ago

When I reconnect the cables, is there any other steps I have to take to make sure the BCM was reset?

Also the audio shop said my alternator was putting out 13 volts. Today when I started the car with the voltmeter the battery jumped to 15 volts so does this say the alternator is doing its job or not necessarily? Before I started the truck, my battery was at 11.9 volts so it dropped more again over night. Not sure how it even started the truck as I thought it needed about 12.4 bolts but maybe because it’s a new battery?

 

[Sackett2622]

Thanks for the tip. Disconnected both terminals a couple hours ago. Also

Thanks for the tip. I disconnected both negative/positive a couple hours ago

When I reconnect the cables, is there any other steps I have to take to make sure the BCM was reset?

Also the audio shop said my alternator was putting out 13 volts. Today when I started the car with the voltmeter the battery jumped to 15 volts so does this say the alternator is doing its job or not necessarily? Before I started the truck, my battery was at 11.9 volts so it dropped more again over night. Not sure how it even started the truck as I thought it needed about 12.4 bolts but maybe because it’s a new battery?

Nothing further is needed once you hook the battery cables back up,fire it up . If the BCM has been reset by disconnecting the battery cables, then your battery will stop running down when the vehicle is off and parked. If it continues to run down, then I would ask around and get prices to have the Mechanic re-flash the BCM to reset it. Finally, if that does not stop the battery drain, you will need to have the BCM replaced. These type of problems are pretty common and it’s a shame that no recall was issued for them. My Tahoe is a 2010 Z71 and has had numerous, random electrical problems. One day, the rear wiper wouldn’t work, the next day it started working and has worked just fine since. I have been stuck so many times with a sudden no start after the Tahoe sat overnight, that I bought a Halo Bolt to jump start it whenever needed and I carry it in the console. The battery cables being off overnight will hopefully do the trick for you. Good luck to you.

 

[Fless]

How exactly has it been determined that the BCM is at fault?

 

[Michigan]

This is the shops wright up of what they did for the parasitic draw a couple weeks ago

“battery dead after sitting overnight.
vehicle would not start in am, fully charged battery and performed draw test. found 170 milliamp draw, should be under 50ma. traced draw to IPC/DIC fuse (instrument panel cluster / driver information center). unplugged instrument cluster and draw dropped to 20ma. removed foglight fuse and IPC/DIC fuses. Ran 10a jumper fuse from fog light fuse voltage leg to IPC/DIC leg. Fog light fuse is ignition voltage, not constant, and will shut down power to the cluster with key removed. fog lights no longer function.”

I took it back in the same week because the battery was still dying. He then ran the jumper fuse to the trailer park brake so I now have my fog light back and he then determined the battery cell may have been damaged. I got a brand new replacement die hard Gold battery and have been having the same problem. Fully charged battery keep dropping down to 12.3 volts in a few hours and then down to 12.0 a few more hours sometimes.

I called him today and he said to remove the trailer light fuse that the jumper was connected to and to connect the jumper directly into that circuit and to monitor it but within a few hours again it dropped down to 12.3 volts from fully charged 12.6 volts. When truck is running it’s showing 15 volts which he said was normal for these trucks

I have no idea what to check for now as he said he didn’t see anything else. In the verge of taking to another shop but just dumping a lot of money into this thing. This has been going on for years

I tried the 24 hour disconnect for the bcm but same thing, battery lost voltage. If I had a bad bcm would I have other symptoms? I believe it’s been getting poor mpg from what it use to get

 

[strutaeng]

Pulling power for the instrument cluster from another switched circuit is kinda of band-aid fix, but works. Basically, the cluster will only have power when switch is ON instead of all the time.

So it sounds like you may have more than one source of parasitic battery drain?