Transmission in high gear from a stop, red light indicactor on 2WD is red on 2005 GMC Sierra 1500

Transmission will be in high gear starting out and will not down shift when I accelerate. The red light at the 2wd selection is red was green before.

Asked by for the 2005 GMC Sierra 1500
2 answers
check tranny fluid levels and condition. review when last serviced. it may be due. bring to tranny shop for diagnostic run. tranny tech. will advise.
scan trans codes and ck fluid level and condition