My dad has a 2006 F150 with 70K miles

I just did caliper/pads/rotors and brake hoses on it yesterday. While doing this I notice the driver side CV axle spins with the tire but the passenger side tire spins freely without the CV moving.

Is this normal? when you engage the 4x4 doe it lock both? or does this mean only the driver side locks making it front one wheel peel? Or is there something hung up keeping the driver side axle engaged? I probably sound like an idiot and I should know this answer but I don't.

 

Get a vacuum pump and connect it to the port on the IWE. With no vac applied it should be locked to the cv axle and the hub and axle turns as a unit. With vac applied the IWE should be unlocked and just the hub turns. The IWE is the aluminum ring behind the hub that the cv joint is going into. There is a double vac line near the top of it, attach the vac pump to the larger line. The smaller one is a vent.

 

Limited knowledge but here's what I know. Hubs are vacuum operated. If vehicle isn't running it will effect the engagement of the hubs. Wouldn't limited slip axles play a role here too. This probably doesn't answer your question but it's a thought.