batt drain, need some help please

[estersj]

i put a test light between the neg cable and post and started pulling fuses. when these fuses are installed the light is on.

hood:
atc
tbc1

seat;
radio
amp
lgm/dsm
ddm
pdm
hvacb


as the truck sits, its pulling 2.51 DCA.. i can remove the radio fuse and it will drop it to 1.67, then once i remove the AMP fuse, it pulls it down to .78.


with the radio on, i can pull the amp fuse and everything goes off.. its factory radio and everything, as far as i know everything on the truck has been untouched it seems

any help would b great!

 

[The_Roadie]

Welcome!

Battery drains are among the toughest problems to solve on our vehicles, because it takes a LONG time to fully go to sleep. Pulling fuses is a misleading way to troubleshoot it, because items like the LGM need to have some power to be able to respond to remote entry keyfob requests. The Onstar module also stays aways a long time, because you might have locked your keys in the vehicle and it's waiting for a call from Onstar to unlock the doors.

There's also a radio and window function called RAP (Retained Accessory Power) that might be active for 15 minutes after you turn off the ignition, but that should go away if you open a door and then close it.

The test light method can also be misleading because some modules can wake up and draw current if the fuse is pulled, then reinserted. Other modules, if they're not fully asleep, can be forced to sleep by pulling the fuse and reinserting it.

My recommendation is to pull some suspect fuses, and then just monitor the voltage every 30 minutes to see if the power drain is still there and drooping the battery voltage. Or put an ammeter across the connection with the battery's positive lead BEFORE turning the ignition off, then disconnecting the battery cable, leaving the ammeter still in place. That preserves the state of the modules. Wait an hour for everything to go go sleep (mostly) then start pulling fuses to see if you can find a high drain item.

That said, if you have an Onstar module installed, and especially if you no longer pay for it, just locate it under the rear seat - passenger's side - and pull its connectors off. Kills it for good, and Onstar's privacy practices are worrisome anyway.

Your ignition switch can also be at fault, leaving power on busses that should be switched. That can also cause parasitic drain.

 

[RayVoy]

The radio and the amp are not connected to switched 12v, both are connected to the battery.

The radio never turns off, it (like a lot of the other electrics) only goes to sleep.

When it "goes to sleep" the current draw falls off to almost zero.

Sounds like yours is not "going to sleep", not an uncommon problem.

Sometimes, a reboot (battery disconnect for 15 min) fixes the problem, sometimes it needs a new amp.



Note to self: gotta type faster to post ahead of Bill

 

[The_Roadie]

Note to self: gotta type faster to post ahead of Bill

Typically 40 WPM on technical items. Faster for pure text. Slower when I have to look something up.

 

[estersj]

as the truck sits, its pulling 2.51 DCA.. i can remove the radio fuse and it will drop it to 1.67, then once i remove the AMP fuse, it pulls it down to .78

Still at .78 it's dropped my batt from 12.xx to 6.xx within 3hr

 

[northcreek]

if you have an Onstar module installed, and especially if you no longer pay for it, just locate it under the rear seat - passenger's side - and pull its connectors off. Kills it for good, and Onstar's privacy practices are worrisome anyway.

I too,do not like the Onstar BS.I'm going to pull the plug on it right now but, would pulling a fuse also be an option?I'm going to look at the wiring diagram and see if the fuse might feed other systems...Mike.

To answer my own question I see that 10A fuse #27 under the pass.seat feeds the Onstar,pulled it and if I get no DTC's tomorrow it will stay that way.

 

[estersj]

as the truck sits, its pulling 2.51 DCA.. i can remove the radio fuse and it will drop it to 1.67, then once i remove the AMP fuse, it pulls it down to .78

Still at .78 it's dropped my batt from 12.xx to 6.xx within 3hr

alright, sittin on the .78 MA i started pulling fuses with the meter hooked up, heres what i came up with until it hit 0.00

.78

-ATC = .73 (.05)
-TBC1 = .66 (.07)
-IPC/DIC = .23 (.43)
-DDM = .17 (.06)
-PDM = .12 (.05)
-LGM = .00 (.12)

 

[The_Roadie]

Are you reading 0.78 A or 0.78 mA?

Even a regular battery (not a deep-discharge) should have an AH capacity of 75 or 100. So even a 1 Amp draw should last 2-3 days before drooping the battery to 6V.

How old is the battery and have you convinced yourself it's not under capacity before blaming parasitic draw for the problem?

Also, pull underhood fuses #34 and #36. They feed the ignition switch, which should not be allowing any power through it when it's off.

 

[estersj]

batt and alt are only a few days old, had them check multiple times. hopeing that was the issue

with every fuse in my truck, im reading 2.50 /amp



my tester is sat on DC/10A

 

[n0kfb]

A 2.5 amp parasitic draw with all the fuses removed? Might you have something rare, like a bad diode in your alternator? Have you had your charging system tested to see if it puts out rated capacity?

Have you pulled your mega fuse and tested current draw?

-- Dan Meyer

 

[The_Roadie]

I repeat my suggestion in post #8.

 

[MMIN]

I'm a still a little confused as to what your actually drawing as you posted some conflicting numbers. So let's start off with what we WANT to see - you should have ALL doors, liftgate, glass, etc closed and the meter set to dc amps interupting the ground lead on the battery. Hood open shouldn't matter as I don't believe any of the US versions got hood switches. Now let the truck sit for at least 30 minutes and check the reading. Normall battery draw is going to be 20 - 40 mA. Depending on vehicle it may range anywhere from 10 - 50 mA but anywhere outside of that range and you have a problem. Anything between 50 and 100mA and you may not notice on a daily driver, but it's still too high. Also once it sits don't open any doors or anything as that voids your testing. Look inside the vehicle for any lights that could be staying on. Check the glovebox light to make sure nothing is blocking the switch. Check all cigarette lighters for any loose change or anything else that could be in them. What is the status of the vehicle otherwise - fully stock has anything been changed?

Also to get your numbers going is it .78 mA or 78 mA?

.78A is 780 milliamps - that's a problem.
.78mA is nothing and really isn't possible

 

[estersj]

like i was sayin, my tester is sat on, DC/10A is what it says..

with EVERY fuse IN my truck, im getting the reading of 2.50, im assuming AMPS?


bill: i can pull these fuses and nothing changes!

 

[MMIN]

with EVERY fuse IN my truck, im getting the reading of 2.50, im assuming AMPS?

The 2.5A is AFTER the truck has sat for a period of time, correct?

From your list the IPC/DIC fuse looks to the biggest offender other than the radio and amp fuses which also are showing abnormally high draw.. Have you tried pulling just that fuse leaving all others in and seeing what changes? Also when pulling a fuse even though you see an instant change, you still want to wait at least a few minutes to see if everything else will shut down.

Also has the current battery been fully discharged at all? Like others mentioned even worst case if you have a 2.5A draw as good battery shouldn't go from 12 to 6 in 3 hours..

 

[estersj]

The 2.5A is AFTER the truck has sat for a period of time, correct?

From your list the IPC/DIC fuse looks to the biggest offender other than the radio and amp fuses which also are showing abnormally high draw.. Have you tried pulling just that fuse leaving all others in and seeing what changes? Also when pulling a fuse even though you see an instant change, you still want to wait at least a few minutes to see if everything else will shut down.

Also has the current battery been fully discharged at all? Like others mentioned even worst case if you have a 2.5A draw as good battery shouldn't go from 12 to 6 in 3 hours..

yeah the batt tests great.. im not exactly sure what happens here, but when i was puttin fuses back in, when i put the IPC/DIC fuse back in when others are out, it will make the voltage jump it then go back down.. NOW when every fuse is in, can pull that fuse, and it'll drop, then when i put it back in it goes up and stays..


ugh my head hurts



now i dont think my radio stays on when doors are closed

 

[The_Roadie]

bill: i can pull these fuses and nothing changes!

Good news, then you don't have a bad ignition switch. You have a bad radio head unit perhaps. Try pulling the connectors off the back of the head unit, but leave the fuses in.

 

[estersj]

That's good to know.

When I unplug my radio, the voltage drops just as if I took out the radio fuse

 

[n0kfb]

like i was sayin, my tester is sat on, DC/10A is what it says..

with EVERY fuse IN my truck, im getting the reading of 2.50, im assuming AMPS?


bill: i can pull these fuses and nothing changes!

Can you post a picture of your tester and where its leads are connected while you are taking the reading?

Thanks!

-- Dan Meyer

 

[estersj]

not an issue dan, as you wish, here they are. its not readin the whole 2.50 because i have fuses taken out at the moment.. but like i say, it usually reads 2.50

 

[estersj]

t t t anyone?

 

[RayVoy]

t t t anyone?

When I unplug my radio, the voltage drops just as if I took out the radio fuse

Sometimes, a reboot (battery disconnect for 15 min) fixes the problem, sometimes it needs a new amp.

If you think the radio is the problem grasshopper, it must changed.

 

[Denali n DOO]

I had a battery drain issue and it was a faulty onstar module that was causing it.