bcm?

[reburg]

i bought an 03 suburban that i was told didn't run as a result of a bad bcm. i finally towed it home and put a battery in it but am not really sure how to diagnose whether it's actually the bcm (they're a little expensive to just throw at the suburban without verification first). i put the key in and turn it to accessory and there is a constant loud buzzing noise under the hood...i'm not sure what exactly the noise is and it's got me a little confused right off because my 03 sierra doesn't do anything of the sort
when i turn the key...i get nothing happening at all. i'm pretty new to gm trucks as i just bought my first (the sierra) in march and now this suburban

another pic of my sierra just because lol

 

[Mooseman]

For proper diagnosis, you would need something like a Tech 2 scanner to check what is really going on with the BCM. Another option would be to get a bluetooth OBD interface and the Car Gauge Pro app to check for all codes, including body codes.

In the meanwhile, how's the battery? Should get it tested to eliminate that. I know on GMT360's, the ignition switch can be a source of electrical gremlins so that could be another place to look.