2ooo safari tranfer case trouble

[vortec6]

I own a 2000 safari AWD, vehicle is stuck in AWD Have Changed transfercase and bought a new encoder motor but still in AWD. Must be a sensor problem engaging the transfer case motor, any thoughts? thanks in advance.

[HeresPaco]

First make sure it is truly in AWD. On these vans the front axles and driveshaft always turn. In fact, if you take the front drive shaft off, your van will roll when the transmission is in park even though the van is normally rear wheel drive when awd mode is commanded off! The transfer case simply has clutches in it which are engaged by the transfer case shift encoder motor to provide power to the front wheels when needed if the rear driveshaft begins to spin faster than the front driveshaft. That motor is controled by the transfer case control module (the TCCM, located in the drivers side kick panel) which senses if there is a difference in the speed of the front and rear driveshafts from 2 speed sensors mounted on the transfer case. (There is one other speed sensor on the case which is the vehicle speed sensor (VSS) that your speedometer operates from and talks to the main engine and transmission control modules). Sometimes that TCCM "goes to sleep" and needs to be "awakened" by pulling the ATC fuse for 30 seconds or so and if that doesn't work then by doing a reprogram (some call it "flashing") of the module by a dealer or capable shop. The cheap scanners that us do it yourselfers usually have can not read anything other than the main engine computer trouble DTC codes. A dealer has the type of scanners that can test and operate each separate component of the other secondary control systems like ABS, Body, AWD, etc. and then they can tell you which part is the one not working properly. It's almost always worth spending the money to have them at least do a scanning diagnosis to tell you what part isn't working instead of trial and error replacement of suspected parts.