Having 4wd problems with 2002 GMC Sierra 4x4. Have the auto 4 wd, 4hi,
4lo, 2hi feature. When select auto 4 wd and/or 4hi the front wheels do not engage. Soon there after the service 4wd light came on, not long after that the indicator lights on the buttons went out. Took it to a local dealer, he said he replaced the modulator and it was fine. Next rainy day selected 4 hi and could spin the rear wheels with no apparent engagement of front wheels. Not getting any service 4wd light yet but 4wd doesn't seem to be working properly. The last time I remember the 4wd working properly was before the front differential was repaired due to a crunching sound coming from the front end when the truck was driven.- posted
18 years ago