I've got a 2002 f150 4x4 and I'm having an issue with the 4x4 not engaging. This is what I've observed so far.

Front drive line spins when switched into 4wd. Also the actuater on the differential moves, and the shift fork is intact and functioning properly. When on jack stands and fork engaged I can spin the front driveline witch in turn spins the drive axles. When the fork and collar are not engaged the wheels do not spin when turning driveline. Also it seemed while engaged the driver side wheel would spin normally and the passenger side would spin and the stop at irregular intervals.
I'd love to go hunting without having to chain up this year. Thanks to all for reading.

 

if you turn the driveshaft and the axles and wheels turn, why do you think it does not work ?
when you turn the dash ****, you sould hear the HI-LO motor in the transfer case engage and then get one yellow light on the dash.. a couple seconds later the solenoids on the dash open and vacuum is switched on the front actuator and the axle engages to the drive shaft. and you get the second light 4 x 4............... what don't you see ?

 

Driving performance tells me it's not working. Poor performance in adverse conditions, no chirping on dry pavement when in 4wd nor do the front wheels kick rocks on gravel as the rears do when accelerating quickly. I've only observed the front driveline spinning while off of jacks stands. I was manually tinkering with it on jackstands (shifting fork rod, spinning drive line with my hand). I have seen the actuater working while running just not 4wd. I believe the front wheels have to rotate before engaging 4wd, thus it would not work on jack stands, or am I mistaken? Maybe the collar isn't fully engaging? Maybe I'll tap the end of the actuater rod... I've never heard it snap, as if seen in vids.

 

Just for reference I've seen it work before on jack stands and not on the ground. Difference in loading/binding on the driveline.

 

spray the actuator and tap on it with a hammer ..... all the way in ... all the way out... make sure it works freely and full travel..... the axle gets its signal AFTER the transfer case shifts to HI or LO.

 

I've concluded it's the tcase...now for the fun stuff. Thanks for the replies.

 

You have no indicated you tested the case motor for movement.
What happens when you engage the dash switch?
You really need to understand the operating sequence before making a final judgement.
The front actuator is the last operation.
The case motor has to advance to the first position in order for the actuator to receive vacuum.
The case motor also engages the case to transmission drive.
You need to check all this out.
Good luck.

 

Tcase motor turns as required, pulled it off while hooked up and had a buddy flip the switch, it performed as expected. Shift fork acuater engaged and collar locked the drive axles. I could spin the front drive line by hand thus turning both wheels. Seeing as how I could spin the front drive line while shift motor on tcase was engaged WITHOUT turning rear drive line, this tells me something in the tcase is wingy, If there's anything wrong with my diagnosis please point it out.

P.s. I also turned the pin on the tcase with pliers while the shift motor was off for inspection.

P.s.s. found a tcase with 62,000 miles on a website called partmyride.com for 170 bucks, so it doesn't scare me too much.

 

Your turning the front DRIVE SHAFT by hand, with the transfer case motor installed and 4 x 4 ENGAGED, and the rear shaft is not turning, right ?

 

If the transfer case motor moves the fork, you will get the light, then you will get vacuum to the front axle, then the axle fork will engage the front end........... if all that happens and you can still move the front drive shaft, then I agree, you have a mechanical problem inside.

 

Correct . Drive shaft, not line. Sorry, I not really up on technical terms.