2008 silverado help

[DONNIE C]

Ok im stumpped and im mechanically inclined i hope it's not what im thinking it may be, i have a 08 silverado the other day letting it sit an idle then it shut down went to crank it back up nothing,had lights an all but no crank turned it off set for a min or so then tryed again cranked up can run around town allday no prob. Unless you sit to long then shut down again .then outside turn the truck in the acc to listen to tunes for an hour went to crank it nothing check the battery it was all good turned it off waited then turn back on an started up. I changed the ignition switch thinking that was it nope,after it did it again i checked gounds,fuses,battery voltage,gonna run codes tomorrow .so im thinking it has to be a bcm or pcm if there is any other ideas or something im looking over tell me. Thank you

[maxwedge]

Pretty sure that truck has a starter relay in the under hood power center, check that also.

[Tech II]

Agree with Max......first place to check is the starter relay.....when vehicle won't crank over, make sure that relay is clicking......if it doesn't try swapping relay.....still doesn't, take the palm of your hand and hit the fuse block while someone turns the key to the crank position....

The BCM, gets a signal from the ig switch.....it sends a signal to the ECM.....the ECM then powers the starter relay....