truck will not run except with radio unplugged does this with old and new radio

What is your question?

checked everything with a scan tool would not connect with ecm replaced ecm same problem. radio also wold not play. Unpluged radio truck starts runs fine. replaced radio same problem.

What makes this problem better or worse?

if radio is pluged in

How long has your 2006 GMC Sierra 1500 had this problem?

a few weeks