Greetings everyone,
In the short time I have been working on my H2, I have come to realize the electrical system is finnicky at best. Lately my Hummer has been sitting under my carport but I do run it for about 30 mins once a week. I leave the battery disconnect unless I am getting ready to start it up due to a parasitic leak. Here are the symptoms which may or may not be related:
I do not use the keyfob for anything.
A couple of months ago the electric door locks started to function less. No matter if you clicked open or shut, the locks would not fully engage/disengage.
The battery was reading under 12.2 volts this weekend, so I put my charger on and gave it a top off to 12.89.
When I put the key in the ignition a status message from the instrument cluster says "driver unknown."
When I try to start, it cranks and catches but goes no further.
I shifted into all gears to check neutral safety switch, and only in neutral does it try to turn over.
Any random error appears on the dash messages including Service 4wd, and battery not charging. Sometimes the engine light is on, other times off. It truly is random.
I have checked fuses for door locks and 4wd ran through some various others but nothing is blown.
Currently nothing on the doors work, locks windows, etc..
Any clues what to do next? I know BCM and ECM are tempermental but I am not savvy enough with electrical stuff to go further. Thanks everyone

-Confused Phatbob

 

Before you go any further disconnect the battery for 30 minutes make sure its fully charged . Also, check ALL your grounds, (ie frame straps ect) Now reconnect your battery and start your troubleshooting from this point.

When a battery in an H2 drops below a specific voltage strange things begin to happen, the BCM forgets things and during the low voltage condition cannot connect or gets error in communicating with items on the bus can sometimes lock them out.

Disconnecting the battery for 30 minutes will reset all of the nodes and the system will gracefully initialize.

 

Thanks for the input 🙂 I plan on messing with the h2 on labor day. Heh. The negative side stays disconnected unless I am driving due to a parasitic leak. Tomorrow I will start from scratch checking grounds and make sure the battery is fully charged. Re reading my post I was very tired and much of it is incoherent. Ha! I will post my progress and see what happens. During this week I have reading up about bad bcm module symptoms. Although I have those, it could very well be a ground. Cross your fingers!

 

does it have aftermarket alarm or audio system, off road lighting or in general non factory electronics good place to start eliminating

 

I may have missed it, what year is your H2?
Have you had the battery tested by a reputable shop, load test and internal resistance?
For the parasitic draw start with the OnStar module fuse, they are notorious for this.

Neal

 

100% support legerwn in his suggestions.

Get the State of Health (SOH) and State of Charge (SOC) checked, the former is a measure of battery capacity, the latter voltage. It's not possible to determine the SOH using a multimeter eg you can have good SOH but low volts (run down) or good SOC but no capacity (like 8 x AAA cells, great volts but no capacity)

Once you know then battery is OK the diagnostics can begin.

Is it an 08/09 by any chance?

 

I appreciate all the input! Here is what has transpired over the last few months for context and progress:
I pulled the onstar fuse at the beginning of summer. I also replaced the battery in April as the old one sat in the PHX heat for 2 years. I have been through the inner and outer fuse boxes a couple times and will continue to pull/check things as I go. I have the factory light bar on top and what I believe is aftermarket dvd system. The few references I find to factory entertainment all show HUMMER on headrest screens which mine does not. The battery drain is still present here and there. My brother mentioned before his passing the drain was intermittent and never completely identified before he ran out of funds although the mechanic believed it may have been related to the gauge cluster.
Here is what I accomplished today: Charged the battery completely, checked the engine block ground, post with braided cable, passenger side harness, and the ground underneath on the frame. All checked out good, cleaned and retightened just to be sure. After leaving the battery completely disconnected for an hour I still show the same driver unknown error, however, I believe a clue has appeared. I always have the interior light bypass pushed in so nothing illuminates. When I hopped in the truck 2 random lights on the gauge cluster were lit, so I tore out the gauge cluster and will send it out for repair. In a fit of rage I also pulled out the BCM and what a task that was! Yikes! At least this way both will be in better working order in a few days. I don't want to give up on the H2 and feel things will resolve, or at least present a reasonable workaround. It was starting/running fine, driven just 2 weeks ago.
My hummer is a 2003.

 

have you taken the amp draw with the truck sitting, everything closed to see what the at rest draw is.
You should also be able to see when all the modules go to sleep and how long it takes them.
Driver unknown is a key issue or ignition issue

Neal