• If you currently own, previously owned or want to own an Avalanche, we welcome you to become a member today. Membership is FREE, register now!

Avalanche starts then dies?


New Member
Apr 1, 2007
Hello I'm new to the forum and need some help!
I have an 2003 Avalanche 1500 with 22,000 miles on it. I've had no problems with it until today. I drove 85 miles yesterday an parked it in the
yard. I went to start it today and it won't stay running. It will start and then 5 to 10 seconds later it will shut off. I have no dome lights,
The guages all read zero, none of the window or door controls work,The key fobs do not work,and the radio does not work. The truck starts every time I turn the key but will not stay running. Also I have no security system installed and nothing tampered with or changed electrically.
Does this sound to be the makings of the "Ignition switch"failed or am I on the wrong path? Please help!        Thanks in advance!
:welcome: to the club  :wave:

Do you have a scan tool? Do you get a check engine light? With all the other problems I think you are on the right track with the ignition switch.
ItsStopher said:
:welcome: to the club? :wave:

Do you have a scan tool? Do you get a check engine light? With all the other problems I think you are on the right track with the ignition switch.
ignition switch even with it cutting off?  possible BCM failure ?  I thought the main switch faults were trans shifting, guages and fault lights.  all of the other stuff doesnt sound like the switch to me.

I'm just guessing.  I'm not a pro at this crap.
Thanks for the replies!
No, I do not have a scan tool. The check engine light, Battery light, security pass light, ABS light, Brake light, and air bag light all come on during the start then the Battery, air bag, and brake lights remain on when the engine dies. I checked a few other things that seem weird also. I can operate the drivers side mirror but not the passenger side. The headlights and their switch work,wipers work, the heater blower works but the shift lever indication shows no selection.
What is a BCM? Also what is it's function
Here is some info on the BCM, but I don't think your problem is there.

Lets try this

1. Remove the underhood junction block cover.
2. Turn ON the ignition, with the engine OFF.
3. Probe the following fuses with a test lamp that is connected to a good ground:

Does the test lamp illuminate on both test points of each fuse?

I got home from work yesterday, tried the truck and it started! Every thing worked right I shut it off and restarted twice. At that point
I decided to bring it in to the repair shop.
At the end of yesterday the tech told me that there were no codes while the engine was running but several when the engine was shut off!
He said it seemed to him that a short was present causing mayham in the electrical system. This short was not allowing the modules to communicate in the system.
ItsStopher, Being the truck started and every thing worked I didn't try your test but, I do appreciate your input. Thanks!

I hope to hear better news today!
This is way out in left field but if you still have the stock battery then this might be the problem. I myself have had minor gremlins related to a 2003 battery. Many others have had issues too. One on mine was the gauges failed to work one morning. I checked fuses and all seemed fine. Pulled the related ones and still no gauges. Then disconected battery for 5 minutes and gauges are working. Did it a couple of times 2 winters ago. All summer no problem then it got cold again. Gauges started to not work. Disconnect the battery reconnect and fine again. On about a 30 degree morning starting sounded weak and went to replace the battery. They tested and said it was fine. I changed it anyways and have not had a single problem even when below zero. I have the feeling the low voltage of the battery causes hardware not to sync up properly between bcm, pcm and such.