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Discussion Starter · #1 ·
Help!! I am lost i have had battery drain problems for awile now. I have taken it to the dealer had the bcm reflashed they could not find the problem. both batteries are good i did a draw test and im showing a 3 amp draw i have gone through every fuse disconnected the glow plug controller and the alternater and still getting the draw. this seems to be intermittent too when the dealer had it they said they werent showing any draw, and it may go a week with no problems then the next morning dead. i dont have a phone charger or anything plugged in. I dont know what else to check. I have a 2007 gmc 2500hd lbz 4x4.
:help
 

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Discussion Starter · #3 ·
well i pulled all the fuses and relays individually and did a draw test and was the draw never lowered for any circuit which makes me think there is a short somewhere before the fuses but any opinions are greatly appreciated
 

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ok i guess i waisted alot of time pulling fuses i was holding my leads and removing them when i pulled fuses which was removing computer charge when i hold it on after a couple min it drops to 8 ma on both batteries so no excessive draw but my batteries are randomly going dead any suggestions?
 

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Help!! I am lost i have had battery drain problems for awile now. I have taken it to the dealer had the bcm reflashed they could not find the problem. both batteries are good i did a draw test and im showing a 3 amp draw i have gone through every fuse disconnected the glow plug controller and the alternater and still getting the draw. this seems to be intermittent too when the dealer had it they said they werent showing any draw, and it may go a week with no problems then the next morning dead. i dont have a phone charger or anything plugged in. I dont know what else to check. I have a 2007 gmc 2500hd lbz 4x4.
:help
3 amps is HUGE, to make sure were all on the same page, when you are doing the draw test, you are disconnecting the - post on both batteries and putting a meter in series on one battery leaving the other disconnected, then waiting 30 -45 minutes for the BCM to fully shut down before taking your reading. then you are pulling out fuses 1 at a time until the draw goes down and still finding no decrease in draw? if you are doing all of those steps to the letter your vehicle has redefined the way electricity works. you must have a load somewhere to create a draw. i suspect that you missed a fuse somewhere.

note that a draw up to 1ish amps is NORMAL until the BCM shuts down (takes about 30 minutes for a GM) my experience is that the dealership should stick with turning wrenches and leave electrical to someone else. i have never seen a dealer mechanic perform a parasitic draw test correctly, or arrive at the correct draw.

i suspect that you have a light that is getting stuck on, maybe a puddle light from a bad door trigger, or a glove box light, something like that. you should be able to trace the issue down by pulling fuses one at a time, the replacing them and moving on to another until you find one that has a significant drop in draw, then find out whats on that fuse and go from there.


Edit: read your last post so the above information is not relevant to you, but maybe to someone else. if you have a 8ma draw (note that that is EXTREMELY low, around 30 is normal) then you should not have a dead battery there is no way a 8ma draw can kill a battery over night, it would take a week or 2, and thats with just 1 battery. when you did your test, did you disconnect the other battery? if not your readings are not valid because the other battery is still supplying current outside of what your meter can read, and with less resistance then your meter is creating meaning that more of the current will flow from the unmetered battery resulting in a false reading. my recommendation would be to check all your door triggers and make sure that none of them are sticky causing the dome or puddle lights to intermittently stay on, which would easily kill your batteries over night.

if all of that checks out you will want to have your alternator load tested, it might be failing or failed and not replenishing the batteries while you drive. you should also have the batteries load tested to be sure, a meter is not the same as a load tester, and your batteries should not drop below 11 volts while cranking the truck, if they do they are either dead or needing to be replaced. as a battery ages its resistance increases causing less current potential. is your truck getting at least 15 minutes of highway driving a day? if not your alternator will not be able to recharge your batteries since alternators do not produce peak current until 2K+ RPM, well over our idle speed. if you dont drive on the highway frequently you could replace the pulley on the alternator with a smaller one, or install a trickle charger along with you block heater to top the batteries off.
 

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When you remove both battery cables, and check the amp draw --- it will be high, because it is loading the computers. After that, it should drop. The way around this, is remove one cable, connect the amp meter, then remove the other battery cable. That should show the draw.

How old are the batteries-??
 

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When you remove both battery cables, and check the amp draw --- it will be high, because it is loading the computers. After that, it should drop. The way around this, is remove one cable, connect the amp meter, then remove the other battery cable. That should show the draw.

How old are the batteries-??
this is true, however its somewhat difficult to ensure the terminal never loses contact with the vehicle while trying to put the meter in series. so in the event that he were to do it that way, he may accidentally disconnect the terminal waking the BCM up causing his results to be very high, despite thinking that he has not woken the module up. since its unlikely that 30 minutes is going to make or break this for him its probably easier to just take the terminal off and wait for BCM shutdown. i have a jumper withe alligator clips on it that bridges the cable to the terminal while i remove it, but thats not a luxury he may have.
 

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Discussion Starter · #8 ·
The batteries are a month old when this first started I just replaced them thinking that's all it was the truck on a normal day does not get a lot of driving none on the highway but this was never a problem before with the same driving habits I know the 8 ma draw seems to be unheard of from what I've been reading and also it drops to that after about 3 min I figured it had something to do with the reprogram the dealer installed this doesn't happen on a daily bases either it may go a week just fine but I have noticed the days it does start the truck is only showing 9v in the cab and it used to show around 12 it shows over 14 while driving I have noticed when I open my rear door the dome light comes on and immediately shuts back off and stays off u less I open the door again
 

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The batteries are a month old when this first started I just replaced them thinking that's all it was the truck on a normal day does not get a lot of driving none on the highway but this was never a problem before with the same driving habits I know the 8 ma draw seems to be unheard of from what I've been reading and also it drops to that after about 3 min I figured it had something to do with the reprogram the dealer installed this doesn't happen on a daily bases either it may go a week just fine but I have noticed the days it does start the truck is only showing 9v in the cab and it used to show around 12 it shows over 14 while driving I have noticed when I open my rear door the dome light comes on and immediately shuts back off and stays off u less I open the door again


pull the fuse for the dome lights and puddle lights and see if your issue goes away.
 
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