F150 4X4 Help?

[olds]

2009
When turning the 4X4 switch, the dash shows the correct selected range and I can feel and hear something mechanical happening.

At times it sounds like a skipping chain. But 4X4 does not engage in 4X4 low or high.

What I've done:
I replaced the vacuum solenoid as it was cheap, no help.

Troubleshooting steps:
Had the wife drive in a snowy field as I watched the front tires. They never engaged.

With both front wheels off the ground and the truck running in park:
2H - neither front axle spins when rolling the tires forward or backwards.

4H - Left axle does not turn while spinning tire in either direction.
Right axle does not spin while rotating the tire forward. But, the axle does rotate when spinning the tire backwards.

What's next?

 

[NutBucket]

Was the vacuum solenoid on the t-case or the front axle? What you should do is put the truck of jackstands, engage 4WD and see if the front driveshaft spins. Then you can narrow down the issue between the axle and the t-case.

 

[olds]

Was the vacuum solenoid on the t-case or the front axle? What you should do is put the truck of jackstands, engage 4WD and see if the front driveshaft spins. Then you can narrow down the issue between the axle and the t-case.

Solenoid is up by the battery

 

[NutBucket]

I mean it sounds like the front hubs aren't locking but it could also be the t-case. I am no expert on those trucks (or any truck really) so I'm just throwing out some basic diagnostic procedures.
Have you gone to the holy grail of repair info (YouTube) yet?

 

[olds]

YouTube says it could be vacuum, IWEs or transfer case motor.
I have a vacuum pump to check vacuum but working on this truck brings me no joy.

 

[NutBucket]

Sounds like it is time to pay someone to do it then.

Even if working on something brings me little joy at least I have joy in the money that stays in my pocket.