I was out on the lake last night and after getting stuck in 6" of hard packed snow, I discovered that my 4WD is not engaging.

When engaging 4WD, I do hear 2 clicks several seconds apart. I've checked the lines from the solenoids to the actuator and did not find any cracks. I have not checked the lines for vacuum yet but...

Last winter while engaging 4WD, I heard a load POP from the front end when I was turning the wheel and engaging 4WD. Ever since then, I haven't been sure if its been engaging but it was confirmed yesterday on the lake.

Based on what I've read, I assume its either the actuator or the shift fork. Is it possible to remove the actuator and test it without disassembling the entire front end?

EDIT: I went under the truck and had my wife engage and disengage the 4WD. The actuator was trying to move (maybe 1/16" inch) but the shift fork wasn't moving. Does this mean the shift fork is bad (frozen) or does this mean the actuator is bad (not enough power to move the fork)?

 

a lot of times they just get rusty or crud on the links. Normally spraying the linkage and shaft with penetrant and tapping with a 5 pound hammer will get it to shift. Dont bend or break anything, but enough force to get parts to move might help.

 

I hosed everything down with penetrating oil and moved things around. I tried removing the actuator but couldn't, even after removing the c-clip. I am getting about 1" of movement now which is marginally better.

How much movement should there be at the actuator and if 1" is normal, does that mean I have a bad shift fork?

 

Im guessing 1 inch is about right. Jack up one front wheel and rotate it... then engage the vacuum cylinder and try to rotate the tire. If the axle engages, you should not be able to turn since it is then connected to the drive shaft which is in park.

 

During the tire rotation test, check the drive shaft by hand to see if they are actually engaged together. The drive shaft may not be "locked" when parked.---------- maybe leaving the tire on the ground and trying to turn the drive shaft is a better idea ?