2006 Hummer H3, About Month Ago, Hummer will not stay on after I starting it, at first it would stay on, but while shifting it to reverse, it starts to acting like it's going to die, then couple seconds later, while trying to reverse with foot on gas pedal, giving it a little gas to prevent it from turning off, car dies. I believe a couple days before that car battery has died, recharged battery, & still does same thing. Battery is connected correctly, checked all fuses, everything looks good. I got it used about 3 years ago, & it never did this... Im positive I have some sort of electrical wiring issue, previous owner has like rear headrest tvs, DVD player under drivers seat, aftermarket radio, I think last 2 years car battery has been having issues dying all time, but until this past month when battery was drained, It had been maybe since May 2024 I had to recharge it. Anyhow, Any suggestions??? I Do have A list of other issues I need help with too, next would be trying to figure out why when I take car to get smogged, they can't find any driving history to do that smog test, & I did that factory driving around & stopping, going on highway maintaining certain speed, did all that lto get car to reset or whatever and still not showing any history??? Ideas???

 

Welcome to HF. You gave us the year, but no MILES.

Test your Battery at rest, you need 12.6 Volts or more. A battery at 11.9 volts is DEAD. Every time you let the Battery get low, it is another nail in the coffin. Charging may get it to work for a while and every additional time you do it will work for a shorter and shorter time. You are describing the death of your Battery. Put a Volt meter on it.

Next. Are you still trying to use the Crappy Azzed OEM Battery Terminal Connectors? If so, cut them off and replace with a quality aftermarket set like Stingers or your favorite brand. First mod to be done to every H3/H3T. Look it up and read about it. Your Battery needs a strong and continuous connection for the Power Control Module (PCM) to properly run your truck. They are subject to minute changes/discrepancies in voltage that will cause electrical Gremlins.

Then you need to look for parasitic drain. Maybe from the aftermarket radio or head rest monitors etc. There are threads here and on the web on how to do that.

A common place to look is by the License Plate light with the rear door open looking in between the chassis and the bumper. Early models had a tight wire harness there that may rub through and short/drain the Battery. Your truck is OLD, that means you have to check the many harness grounds for corrosion and clean them.

When was the last time you cleaned your Throttle Body (TB) with TB cleaner? Your Mass Air Flow sensor (MAF) with MAF cleaner?

 

Thank You For Taking Time To Answer My Questions, Miles On Car: 146,153...I'm Headed Outside To Attempt Some Possible Solutions...But Dont Go To Far, Cuz I Know I'm Gonna Need A Couple More Questions I Have With Problems On this Hummer