03 gmc 8.1 starts then dies, PLEASE HELP

[Foxtrott4646]

The truck starts for less than a second with no problem before dying with a display message of "BATTERY NOT CHARGING" truck wont run long enough for me to test alternator, but battery has good power so I figured it should at least run for a little off the battery but to no avail, im going to take the alternator down and get it tested, but I still don't see why it wouldn't run off the battery

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[DAVe3283]

The "battery not charging" message is probably because the engine died, not why it died. The alternator might be fine.

You'll need to check the basics:
* Security (does the security light go out or stay on, etc.)
* Fuel pressure
* Etc.

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[1FastBrick]

I believe those were notorious for cam or crank sensor issues too. IF you have a capable scan tool, see if shows the signal while cranking to rule that out.