I got the "Service 4WD" message this morning for the first time.
Was in 2Hi. Indicator light on the switch was on when I left the house.
After I made a stop, I saw the "Service 4WD" message on the DIC. First time that came up.
It is still driving in 2Hi, just fine.
No indicator lights on the switch and nothing happens pushing buttons.
I won't be able to get the Tech 2 out until Thursday or Friday, but I'll see what I can find out and whether the switch is doing anything.
Probably the switch.
I have no codes for brakes, ABS or anything else.
I'll Let you know if I find anything.