I recently purchased a 2000 S-15 Jimmy. 4wd appeared to be working OK when I test drove it. About 2 weeks later the SERVICE 4WD light came on and now it will not shift into Auto 4WD, 4WD HI, or 4WD LO. The indicator light on the dash stays in 2WD HI no matter which button I push. The transfer case appears to be in 4WD HI. I say this because I put it up on jack stands, started it up and put it in gear. The rear wheels turn, and the drive shaft from the T-case to the front axle is turning. The front axle shafts to the wheels are NOT turning.
Any suggestions as to where to start?