I have a 2009 Trailblazer and during the cold months the maintenance light for the 4WD comes on or it attempts to change to either AW, 4HI, or 4LO. It isn't a push button that I have read in previous threads but a ****. This only happens when driving and is sporadic. What could be causing the issues?

 

When it happens does it do it for a while or just for a moment? The **** is still an electrical issue so I would recommend pulling it and checking the resistance on the posts in the **** itself. Basically you will be checking each post to see if there is an open in the ****. So you'll have to get a diagram to find which wire goes to which post. So you'll see where the signal post allows voltage to go to. So basically if there two sets of posts show signal through them at the same setting ("N" "2WD" "4HI" "4LO"). Each position should (check diagram in case) only allow the signal to come through in one set of posts. If this is good check the unit on the case. I am unfamiliar with the case unit on this particular model so you'll probably want a service manual to guide you. If that is good, it's possible that the harness has a short or a loose ground. If there is a relay on the system make sure to check that as well. If need be swap another relay that you know is good and see if that changes anything. Unfortunately, this issue is one that could be a quick fix or a laborious diagnostic. I welcome others who may be more acquainted with this model to chime in and add better information. Let me know if you figure anything else out and keep us updated. Thank you.