2005 Denali No crank no start

[Doubeleive]

Hi guys, new to the forum. 2004 Yukon XL Denali. May I ask what the BCM is please? Having this same issue. Thanks in advance.

the bcm is unlikely to be your issue if you have a dead battery, bad battery/bad alternator.
if neither of those then start checking battery cables and grounds.
if it dies over night or over a period of a couple days then do a draw test, things like a aftermarket radio or amp or other things plugged into a cigarette port can kill the battery.

 

[rockola1971]

the bcm is unlikely to be your issue if you have a dead battery, bad battery/bad alternator.
if neither of those then start checking battery cables and grounds.
if it dies over night or over a period of a couple days then do a draw test, things like a aftermarket radio or amp or other things plugged into a cigarette port can kill the battery.

BCM not going to sleep causes the battery to die overnight also. Our chassis is notorious for this problem. A shorted output transistor in the BCM itself will cause dead battery overnight and also corroded or missing ground for the BCM will also cause this since it has no Zero reference available with a corroded or missing ground. And of course the shorted diode pack in the alternator or shorted cell in the battery will also cause the same symptom. A clamp on ammeter will rule the alternator out in like 15 seconds or less.

 

[Doubeleive]

BCM not going to sleep causes the battery to die overnight also. Our chassis is notorious for this problem. A shorted output transistor in the BCM itself will cause dead battery overnight and also corroded or missing ground for the BCM will also cause this since it has no Zero reference available with a corroded or missing ground. And of course the shorted diode pack in the alternator or shorted cell in the battery will also cause the same symptom. A clamp on ammeter will rule the alternator out in like 15 seconds or less.

this is why I also stated to do a draw test, just start pulling fuses until the draw stops
normally a dead battery is either a bad battery, bad alternator, corroded/bad battery cables/ground.
other more common causes are aftermarket equipment installed (causing a short) or something is plugged in.
BCM going bad is rare (not impossible) but it would be one of the last things I would check if nothing else panned out, just a process of elimination.