front differential
 

1993 K5 Blazer, front diff will not engage, transfer box engages properly.

RE: front differential
 

Is it AUTO HUBS or MANUAL? I assume the driveline is installed. Without more info I would guess a problem with one or both hubs.

RE: front differential
 

check vacuum lines

RE: front differential
 

My question also. How do you know that the transfer case is engaged? Do you have the truck jacked up and the front drive shaft and axle shafts are turning?
My front driveshaft will turn if I'm just rolling down the road in 2WD.

RE: front differential
 

My 93 K5 has auto hub engage, I can turn the front drive shaft by hand when the transfer case is not engaged. When I engage the transfer case the front drive shaft will not turn by hand, this is why I believe the transfer case is engaging. The front differential has two electrical connections going into it, I'm not sure how the front hubs engage automatically, I am assuming it is a function in the differential but not sure. I have looked in Motors and Chiltons and neither cover the front drive train. I haven't seen any vacuum lines going to the front differential so not sure if it uses vacuum. Thanks for any ideas.

RE: front differential
 

If it is anything like my dad's '94 K2500 pickup, you have an electro-magnet that is energized to engage the front diff. There are no auto hubs in the traditional sense as the disconnect happens in the diff itself. The replacement engagement module is a stepper motor which has a positive engage/disengage where the older electro-magnet modules are iffy when they get old/worn/sticky. I would bet that is your problem!

RE: front differential
 

swartll, thanks for the info. do you know what is required to change this part, does the diff. have to be opened up and disassembled.

RE: front differential
 

It should have like a 1.25" hex on it or something large like that (it has been like 6 years or so since we changed it on my dad's truck). The replacement is going to be all plastic IIRC and I can't quite remember what the original one looked like to be honest... It should be near where the passenger side extension tube bolts to the center differential section on the passenger side of the diff.

RE: front differential
 

Swartlkk, Do you have any idea what tells the unit to engage, there doesn't seem to be any electrical connection from the shifter, is it some kind of sensor, or do you have an idea where I can find a book on how it works. Like I said no detail in chilton book.

RE: front differential
 

There should be a switch in the console on the floor of your truck. I don't have my references with me at work, but I will try to remember to post back up when I get a chance this weekend.