Need Help Trouble Shooting Front Diff Actuator

hoorders · May 11, 2008

Im hoping one of you GM techs can shed some light on this.

The last few oil changes.....while I was under my truck, ive noticed that I cannot spin my front drive shaft by hand. Feels engaged. My 4wd works just fine though. So I decided to check a few things out.....I dropped the shaft off of the front diff and it spins fine.....so this tells me its not engaged at the transfer case....I put it back on the diff and removed it from the transfer case and I cannot spin it.....so seems like front diff is engaged......Ive replaced both the dash 4wd selector switch and the front diff actuator.

Where does the front diff actuator get the signal from?

How can I trouble shoot this, check wiring. etc???

Thanks very much!!

hoorders · May 12, 2008

OK, Check the 4WD fuse in the left IP. Next, I would take the actuator out and see if it is extended and also see if the plunger in the front diff moves freely. also, while you are down there, check for any obvious wire/harness damage.

Allright I will check the fuse out........I did have my actuator out and it is fully extended.....I never checked if the plunger in the diff moves freely though......I will check that out.

Another thing to note is that when I put the new actuator in a while back, I first plugged it in to the wiring harness and switched the truck from 2wd to 4wd and the plunger did not react it just stayed in then out position.....I could only hear the transfer case engaging and disengaging.

Thanks.

hoorders · May 11, 2008

Well for starters, need some more info. 1500 or 2500, 3 or 4 buttons, that kind of thing.

Sorry about that........its a 1500.....the switch has auto4wd - 2wd - 4hi - 4low - N - .......all 4wd drive setting work.....its just the front diff actuator that stays in the out position.

Thanks.

cammiller · May 11, 2008

OK, Check the 4WD fuse in the left IP. Next, I would take the actuator out and see if it is extended and also see if the plunger in the front diff moves freely. also, while you are down there, check for any obvious wire/harness damage.