4x4 not working

[Rancelot211]

My 4x4 on my lmm isn't engaging. Used it once last year. Light on knob lights up. I can hear the transfer case engaging. I pulled the acuator out of the diff and it is extending. Same thing with 4 hi and low. Truck is jumpy in low so I'm assuming the t case is working properly. Any ideas on what else to try?

 

[DefiantArms]

I've pulled the drive shafts before to see if the problem is in the case or the front diff. It was on a buddy's 1500 a long time ago. He had a problem in the diff I can't seem to remember what it was. I'm getting old

 

[NC-smokinlmm]

Actuator is weak and not engaging the front axle. Replace it and it should fix the issuse.

 

[Rancelot211]

Replacing it was my next step. Figured I'd ask before I wasted my time and 80$

 

[Chevy1925]

Replacing it was my next step. Figured I'd ask before I wasted my time and 80$

put it in 4wd, lift the RF tire off the ground and see if you can spin it. if so, its the actuator

 

[Rancelot211]

Up top actuator didn't fix it

 

[JoshH]

Put the truck in 4wd, jack up the front end, try to spin the driveshaft. If it spins, the problem is in the transfer case. If it doesn't spin, the problem is in the front axle.

 

[Rancelot211]

drive shaft doesnt spin. what should i look for in the front diff? never had to mess with the front diff on anything. snap on solus show that the front diff is locking but says the actuator is inactive but i can hear it coming out., actuator volts drop to 0 when i lock it in 4x4 and it says 7 volts when in 2h.

 

[Chevy1925]

Up top actuator didn't fix it

And what happens when you do as I explained?

 

[Rancelot211]

And what happens when you do as I explained?

Been away for awhile and forgot about it. Had my buddy look at it while I was on vacation. Finally got around to jacking the front up today.

 

[JoshH]

The collar or the fork could be broken. Take the actuator out and manually push the plunger by hand while spinning the driveshaft.

 

[Rancelot211]

Will do that Saturday. What it mean if it goes in or if it doesn't?

 

[WVRigrat05]

It means 170 bucks and about an hours work.

 

[WVRigrat05]

http://www.duramaxdiesels.com/forum/showthread.php?t=28158&highlight=LMM+front+diff

http://www.duramaxdiesels.com/forum/showthread.php?t=69517