LS 6.2L tech

[Baconator]

;n111004]unplug the MAF, just run it speed density and see if it still does it

Forgot to add I tried this yesterday when it died, no change. the MAF reading looks the same when its cranking and not starting vs when its cranking and starting.
Im starting to wonder if its the ECU

 

[GM Guy]

I replaced the alternator, and battery ground cable and loosened and cleaned the grounds that I could find on the engine.
Still does it, only when hot, voltage drops to 12.9-13.1V and stumbles and dies at idle.
No idea where to go from here, this damn thing has left us stranded so many times now Ive lost count.

To throw another curve at you, GM cuts the alternator out of the picture in certain conditions and just runs the battery down to whatever point and then commands the alternator to charge again. 12.6 is not unusual to see in my work truck. On the early systems hitting the tow/haul button would override that, but not on newer trucks, I forget what year that changed.

Alex.