Service 4WD light stays on. There is a roar underneath the car. Suburban Z71
Welcome. What year is your suburban?
Ok. the usual issue on these 4wd systems is the sensor located in the side of the transfer case. The sensor fails and sends a false reading which causes the message and likely your noise. The best way to confirm is to have the chassis scanned for codes. The usual code is c0327. HERE are instructions for replacing that sensor.
GM Grand Master Technician 2007. 11 years experience.