Service 4WD light 2000 Silverado

I have a 2000 Silverado with push button 4 wheel drive selection.
Twice now the service 4WD light has come on, and I am unable to shift from 2wd to 4wd or auto 4wd. Problem went away both times after one or 2
restarts.
I have scanned for codes a few days later and there are none. Shouldn't codes be stored in memory for a while?
Any ideas what the problem might be?
Thanks in advance!
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snipped-for-privacy@nowhere.com wrote:

Very, very common problem.....
Cold solder joints on your dash 4x4 push buttons....
Replace push button module for $50 or resolder..
I had that prob in my 2000 5.3 Ext Z-71 2 years ago..
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