Hey guys I just bought at 2001 Chevy trailblazer 4 door 4x4. Now I live and Florida and the dealer I bought it from told me it was originally from Ohio so there is some rust. Now I filled her up with gas and started to drive. As I take off from a stop light I get a real bad front end shake up to about 30 mph. It seemed to me as if the front drive shaft from transfer case to front differential was out of balance or lost one of it weights. But after driving 20 miles and using a 1/4 tank of gas I knew there was a problem. So I put my scan tool on it and it tells me that the transfer case is locked but the front differential is not and even though the push button reads for 2hi mode. I unplugged the transfer case module but it didn't seem to do a thing to help it. Tomorrow morning I plan on disconnecting the battery for 10-15 min and look for any fuses to pull. Also I read online that the encoder motor could be bad? Does anyone know what the problem could be or anything else I could do to test it? Any and all help is appreciated.

 

How many buttons are there on the dash for the 4wd selector switch?

If you have an Auto4wd button, then the front driveshaft will always spin and your problem could be a bad universal/cv joint in the front driveshaft.