4wd not working

[Zenchal26]

 

Hey can’t get this 4wd high to work on this 1994 1 ton chevy. Goes into 4 low but not high, has shifter on floor. Replaced actuator on front axle with the upgraded motorized one. Replaced switch on transfer case. Shift to low can hear actuator work and lights on shifter light up. Switch from 2 to 4 high no noise from actuator no light. Is there any other electrical components to the system or am I chasing wires to find broken ones at this point?

[davester]

So you can physically shift the lever into 4hi, but it doesn't seem like you are in 4hi?

 

I would suggest first testing what the system is actually doing, by lifting up one of the front wheels (safely, using a jackstand), and shift into 4hi with the key on.

 

See if you can rotate the front driveshaft, and then see if you can rotate the lifted wheel (with the transmission in park, or in gear if you have a stick).

 

If you can't spin either, then you are in 4wd (and most likely in 4hi).

If the front driveshaft doesn't spin, but the lifted wheel does, then I would test the 4wd sensor on the transfer case to see if it indicates being in 4wd, as the system overall works right for 4lo, but not 4hi, and that's where it happens slightly differently between the two modes (a lever inside the TC is in a different position).  It might be the sensor or a wiring thing that just happens to work for 4lo but not 4hi, but more likely it's that lever inside the TC that isn't pushing that sensor right (lever or bushing is worn perhaps).

[Zenchal26]

So seems the switch on the transfer case is not long enough. If I pull the switch out of the case and manually push the switch with my hand the axle will lock in? Are there different switches for the different t cases? I have the borg Warner case took me a few trys at the store just to find an output seal that was the right size. 

[davester]

That I have no idea about.  Given that you say 4lo works, I would say the switch is the right length and works (as it activates the actuator in the front axle), but for some reason it's not happening for 4hi.  You could perhaps take out the sensor and look in the hole (either directly or with an inspection camera, or even a cell phone), and see what's the difference in there between 4hi and 4lo.  Perhaps even measure it to see what the difference is.