Hi folks, I have a strange problem with my 04 trailbazer, 4.2 I6 4x4. I use to car for long distance highway trips about once a month (600 miles round trip). After about 150 miles, the service 4wd light comes on. Some back story on the car, The 4wd has not worked for several years. I put the car in neutral, select a 4wd position, I hear the transfer case making the usual noises and the selector switch properly stays lit on 4wd lo and hi, but I know that the front wheels aren't getting power. Now back to the light. Like I said, the service 4wd pops on after about 150 miles on the highway and will stay lit until I turn the car off. once I turn it back on, the light is gone and will come back after about another 150 miles. I have the car in 2wd, never in auto 4w. Now, last time I changed the oil I noticed some grease spray around the inner front CV boot on the drivers side. Could this be throwing the service 4wd code and have something to do with my 4wd not working? I'm slightly concerned about the front diff now as well. Could the leak be coming from there? Could long high way trips in 2wd be damaging the front diff? Not sure if the front diff is moving when in 2wd. Any thoughts here appreciated.