Hey guys,
Im super excited I finally got my FIRST Hummer was super excited I found such a decent deal on a 08 Model. However engines a little rough at idle but I think it just needs a tune up. Not the issue for the day unfortunately I wish this were that simple.

Actual Issue: Dead Battery - Replaced with brand new bat. NR 12.58 R 13.98 or so. Battery and Alternator appear to be in good shape for now. However I have a .84-.86 ma pull on the battery long after shutting the engine off.

Now I have done a Parasitic test constant and pulled all fuses gonna do it once more come day light just to double check myself. However if its not a FUSE in any of the three FUSE boxes where do I go from there. Ive read about using a transmitter of some sort but that will require a crap load of work to properly trace all or most of the vehicles wires/harnesses.

Ideas?

Thanks in advance hope this isn't a redundant post. Currently just disconnected the bat. till morning.

Muddvain

 

Start with anything aftermarket. Alarms, remote start, head units, light bars, dvd players, etc.

 

Everything as far as I can tell is all stock and I haven't done anything to it. Actually why I went with this particular Hummer. Thanks for the ideas though for sure will be looking for weird placed wires as I search.

 

Check for an update for the BCM.

https://tis2web.service.gm.com/tis2web/

 

Onstar will have the following draws.
IGN ON - 240 to 400 mA
IGN OFF - 3 to 20 mA for 48 hours
IGN OFF - after 48 hours (up to 120 hours on certain VCP's) - 0.2 to 0.8 mA

The attached is a pdf from the GM eSi on troubleshooting parasitic draw on an 08 H2.

 

Most recent UPDATE -
Short story is I was testing it wrong figured out the (VCIM) - NEW OEM PART# 25907274 AC DELCO this is the updated part number. Dealer cost would've been $385.00
Continued to look for an alternative found the FUSE labelled (ONSTAR) go figure removed it and tested it again draw dropped .38 mA leaving aprox .14-.24 not sure what else is drawing but I also didn't give the system the full 60 minutes the system needs to shut itself completely down.

FYI on my 08 Hummer H2 I wasn't able to just disconnect the whole unit and leave it out without multiple error codes such as (ABS, EBRAKE, service 4wd, ect…) so obviously cant just remove it. However after removing the FUSE and leaving the unit plugged in and computer reset no codes or anything were on the dash and the .38 mA parasitic draw was eliminated.

Hopefully this information helps some of yall out.
FYI also the Module is under the radio not to bad to get too I actually dropped the cables under the center console and worked from there so I could close up my dash and unplug and plug it in when needed for testing purposes.

Thanks for the ideas and such will be testing the volts on the battery daily to see how much if any it continues to drop now.

 

I had to do the same thing and leave my onstar fuse pulled. Sometimes it will keep searching for a satellite connection and if it can't find one it will continue to do it until it kills the battery.

 

I know this thread is old but this is some useful information for anyone stumbling by. This is the only case on the 08-09 that I’ve heard of on star actually being the issue, it seems to usually only happen to the 03-07s.

my 08 had the same 240-250 ma draw when everything is off and the modules have gone to sleep. With some fuse pulling I discovered that is actually the BCM. Even after multiple hours it still draws that amount. I assume it will eventually go to sleep after 4-5hrs or something like that.

the BCM fuse is located in the instrument panel fuse block in behind the driver side panel between the dash and the door. I found it helpful to pull that when checking for parasitic draws. If the current goes from 240-250ma to 40-50ma after pulling, then all is normal.

 

I had this issue and my passenger seat motor was stuck on. It was hot and making a slight noise. Moved the seat and now no more drain.