I would like to ask a question if I may regarding my 02' 4.3 4dr blazer that won't engage the front differential.


Here's what's happening. The buttons on the dash light up properly when shifting to 4WD Hi and Lo and back to 2WD. The Txfr case motor engages and the vacuum switch opens pulling in the vacuum actuator under the battery (replaced last week because of a pin hole in the bellows). The new actuator moves the cable approximately 5/8 inch measured at the actuator bracket. The cable is not broken because I could feel it move and heard a click in the diff. when changing the actuator.


There are no other vacuum leaks that I can find. There was 2 others and they have been repaired. The seals on the txfr case (NP 233) and the back of the trans were changed last Fall because of leakage from the trans to the txfr case. New bearings in the case too. The vac switch was also replaced and all the fluid was blown from the vacuum lines with compressed air. 4WD worked after this repair. Worked well too.


I'm reasonably positive the issue is in the Diff because it doesn't get the tight feel in a turn in a sharp turn. So I checked the following.


The transfer case motor engages the front driveshaft determined by elevating the truck, (all 4 wheels off the ground) engaging the motor and the front shaft is locked in at the Txfr case. At the same time, the drive axles are free -rotating the front drive shaft will not rotate the front axles.


I've never taken a differential apart before. I'm imagining there is a fork and or some kind of sliding gear or spline that the cable engages via the vacuum actuator. I suspect that the pin hole in the actuator may have cause a partial engagement and consequently wore out or broke parts in the diff.


*Is/Are these replaceable part(s)?
*Has anyone seen a failure like this before? I found nothing in my search for answers.
*Should I repair this unit or start looking for a replacement front Diff? or *Is there some other thing I should look at first?
*Is there a exploded view drawing of this Diff anywhere?


I'm not a pro mechanic but I won't back away from the task if it's do-able. Just want some info because I need to do this in one day because this is my ride to work.


Any help is greatly appreciated. Thanks