5.4l 4X4 electric shift Lariat.

Shifts into 4WD just fine (high and low modes). However, it's reluctant to shift out of 4WD. Usually, stopping, shifting into park, then putting it into reverse and backing up a few feet causes it to shift back into 2WD.

Any ideas on what's wrong and how to fix it?

Also, it drive nice and smooth in 2WD, but have annoying driveline vibration in 4WD high.

Any ideas on that one?

Thanks,

Jim

 

Your description suggest two different issues.
The 4wd disengagement could be the front actuator has an issue or the vacuum line to retract the axle coupling has a leak at some point such that the actuator has less pull. otherwise it seems to be all working as normal.
Test the actuator with a hand vac pump to check for relative operation both ways and ability to hold a vacuum on that port, then the line back to the check valve and solenoid on the firewall.
The Actuator mechanics could be corroded of pack up with dirt and need some lube to free it up..
Putting in reverse takes the friction pressure off the 'coupling' letting the actuator pull off the coupling inside the axle housing.
.
Vibration: Could be tire diameter too much different from the rear or side to side, CV joint, front bearing pack, drive shaft issue or even the carrier bearings.
.
Get the disengagement resolved first then the vibration issue.
Good luck,

 

So, there are vacuum lines on the shifter motor actuator? I assumed it was all electric because of the electric switch on the dash. Anyone have pics of these vacuum lines?

thanks for the reply; anyone else?

Jim

 

Yes it's vacuum operated and not a motor.
Good luck.