my G20 with a 6.2L wont start. its not fuel because it wont even turn over you turn the key and the battery drains but the starter doesn't turn so i think its either a starter solenoid or the starter itself any one have an idea?  

I WOULD START WITH THE STARTER, TAKE THE STARTER TO AN AUTO-PARTS STORE AND HAVE THEM CHECK IT, IF STARTER IS GOOD, CHECK THE IGNITION SWITCH, THAT ONCE WENT-OUT ON ME AND MY TRUCK DIDN'T START.  

I have had several GM diesels and still have one 5.7L, first thing I would do is remove all battery cables and clean connectors. On the older chevy's, both battery pos terminals were tied together on left battery, make sure there is a spacer between pos leads before reconnecting, assuming batteries are good. If it still don't turn over, have someone turn key to start while you tap on starter housing with hammer, but not too hard. Hope this helps, let me know  

I have a similar issue with my M1009, but I have no dash lights either (WIF, GP etc.) when it happens.  It's intermittent, but obviously a relay/solenoid problem.  If I grab the wire harness and shake it, with the key on, I can hear the relay clicking, and the dash lights come on.  I haven't tracked down the culprit yet, because it's intermittent, but thinking GP relay or starter relay.