When I push the 4Hi or 4Lo switch the indicator light flashes (never goes solid on). Can you tell me what I am doing wrong?
You can try switching it while moving very slowly, sometimes if the 4X4 isn't used as recommended in the manual it won't shift as it should. If that don't work then check the transfer case motor it maybe bad.
Search GMC Sierra 1500 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
GMC Sierra 1500 Experts