Front wheels not locking (4wd)

[corey1]

When I press the button to go into 4hi or 4lo, I can hear the 4wd engage and can feel it gear down while I drive but when i am on sand or snow it appears that the front tires arent locked in. They wont spin or pull.

[mjohn]

you say on snow...
I have 1993 Jimmy 4.3 Wseries...4WD
and when ice fishing last year and on the lake...in several inches of snow...I could not get the 4WD to engage for it has a thermal unit...which will not engage when cold...

[BobcatAZ]

You didn't say what year. Some models/years have a vacuum unit under the battery, which locks the front axle via a cable. You might check the unit to see if it hasn't been affected by acid.

[96jimmy4wd]

I had the same problem, battery had leaked onto the cable and the vaccum diaphram the cable is longer (48")on the older models because it was mounted on the rh fender the newer ones are 37" but the older one will work on a newer one