Hello, first post long time lurker.

Two nights ago we had a nasty winter storm here in Philly. My wife parks the Hummer and turns off the car. Later that night in the fury of the storm we see that the rear brake lights (just the two brake lights, not including the third light above the spare tire) are on. So we go out to investigate. Hop in the cab and see that the 4 ways and the interior lights are flashing in tandem. She turns the key to on and off and the lights stop flashing and the brake light goes out.

Come morning I go out to the Hummer and it will not start. No chimes when the door is open, no interior lights. Turn the key, nothing happens. However now the key is stuck in the ignition. Great. I go out and get a new battery, install it and fire it up. Hummer starts, take it for a test drive and everything, no issues.

Today I go out to start it nothing. Just like before, no interior lights, no chimes and the key is stuck in the ignition.

So I think it is the alternator. However, admittedly I am not very knowledgeable about cars. So my fellow Hummer enthusiasts what do you think could be the cause? Is it the alternator or something much more malign?

tl;dr Hummer wont start, keys stuck in ignition, replaced battery, same issues.

Thanks in advance!

 

get a volt meter. engine off volts appx 12. engine on volts go up to 15,then drop to 13-14.


if lights stay on you have trouble that is hard to figure without testing, unhooking stuff.


normal drain with doors closed,open one batt cable,connect ma meter = appx 110 milliamp. 1/10 amp.

 

First, have it scanned for any possible code.

It sound like you could have a BCM issue, they can go bad, and can act weird if they get wet. Do you have a sunroof and did you ever notice the passenger side floor was wet?

 

Thanks. We are gonna jump it then head out to get the codes pulled. Will post em once we have them.

Thanks again for your suggestions!

 

Sorry for the double post. Yes there is a sunroof, can not recall passenger side wet. The drain was clogged and we did have some water flow down the inside of the windshield though.

 

The BCM is behind the glove box by the passenger kick panel and are often the victim of the dreaded sun roof plugged drains. If you got it wet, that is you problem. Sometimes they dry out and are OK for a long while, or they have intermittent issues, and other times they turn to toast.

 

sounds like it could be the battery terminals the oem are junk and it will cause all sorts if issues. H3 are electrical mysteries lol. Ours did the same thing with the lights flashing, our lights on the a/c ***** were also flashing and the gauges and radio were going crazy. It ended up being the battery terminal had a very hard to see crack in it.

 

This is also good stuff, the OEM battery terminals are CRAP. Get a quality aftermarket set.

Kudos mudiak!