Posted by Traveler on October 24, 19100 at 08:12:57:
In Reply to: FRONT DIFF. ON '95 BURB posted by Mikie on October 24, 19100 at 07:45:42:
The disconnect is in the front diff. Stock is the Thermal Actuator that didn't last too well. It is typically upgraded to the electromechanical model used '98 and later.
The transfer case is still driving the drive shaft to the front but the diff disconnect allows the axles to free wheel relative to the ring gear.
If I recall correctly, moving the lever from 2HI to 4 HI does the following: Sends power to the thermal actuator, feedback switch closure illuminates the 4WD pictoral, ABS system flagged for 4WD.
4LO works the same and in addition mechanically introduces a 2.72:1 gear reduction and flags the PCM and ABS that 4LO is selected.
This is why you never get any gear grinding between 2HI and 4HI.