Can't get her into 4WD (3 Viewers)

[CBFJ]

Don’t go by the light. It could’ve burned out, bad path to ground, etc.

Pretty sure hubs unlocked, trans in neutral, you can still spin the front driveshaft by hand in 4wd because there’s nothing stopping it from spinning.

Lock the hubs, put it in 4 and drive it, turn tight, you’ll know if it’s in 4 or not.

X2 on the light. Mine used to work, doesn't anymore, but 4WD works.

 

[Living in the Past]

The 4 bolts hold the housing that contains the rail and fork, not sure what holds the vac accuator on or if it has to be removed to get the fork housing off.

While unit comes off with the four bolts. Housing is cast with the bottom part of the diaphragm.

Don’t go by the light. It could’ve burned out, bad path to ground, etc.

Pretty sure hubs unlocked, trans in neutral, you can still spin the front driveshaft by hand in 4wd because there’s nothing stopping it from spinning.

Lock the hubs, put it in 4 and drive it, turn tight, you’ll know if it’s in 4 or not.

If the transfer case is in 4WD and rear driveshaft is connected the back driveshaft has to spin with the front driveshaft. The collar connects to two together.

 

[Living in the Past]

X2 on the light. Mine used to work, doesn't anymore, but 4WD works.

Believe the OP says the front driveshaft spins free in both two wheel and four wheel drive. If the hubs are in free wheel and the driveshaft spins it's not in 4WD if the back driveshaft is installed and wheels on the ground.

 

[Skreddy]

If the transfer case is in 4WD and rear driveshaft is connected the back driveshaft has to spin with the front driveshaft. The collar connects to two together.

Good call on that.

 

[illinikev]

On my 68, pull the knob if the green light doesn’t light, just drive forward a bit and it engages…..about a 50, 50 chance the splines are lined up to allow the cog to slip over the splines.
Also, I engage the hubs befor pulling the knob. Originally, when you pulled the under dash lever to low range, there was a linkage that pulled the knob out to ensure you were in 4WD in low range….mine abandoned been removed.

ok i will try this as well. it's interesting, there's two little bumps on the transfer case lever so it does seem like it's missing something.

 

[John McVicker]

I’ve had to do what @Mark Jennings suggest several times. Always worked. I’ve since rebuilt the T-Case & haven’t had the issue since the rebuild.

Don’t really know what fixed it…or the cause, but doing as Mark suggest might get you going.