Hi! I'm new here, so I hope I'm doing this the right way: My Suburban has this "button controlled 4x4" as I call it. The 2H and 4H have no problem functioning. When I try the 4L the light just blinks and it does not engage. I do try this in low speed or standing and in neutral of the gearbox. I have an OBDII code reader, but it doesn't give any code related to this problem. Is there any way for me (not being an expert) to determine the cause for this problem?

 

with the truck stopped place the trans in neutral then shift into 4 low in a few seconds it should shift.