F 150 4wd problem

[backlash 1]

2005 f 150 40,000 mi. Shift on the fly engages into 4wd normally, when I go to switch it back to 2wd I don't think it is disengaging completely, because I get this vibration in the steering and a loud road hum sound. Switch it back to 4wd, hum and vibration quit. I usually have to switch back and forth several time before it is normal. I can hear the clunk when it engages and I think I used to hear it when it disengaged, but no more. What is wrong?

[upnorth]

Are you backing off the gas when or shortly after you shift out of 4 wheel?

[backlash 1]

Yes I am, I bought the truck new, and it just started doing this last week.

[shizzy]

Are you backing off the gas when or shortly after you shift out of 4 wheel?

X2. I have owned a few trucks that seemed to disingage better if you took your foot off the gas for a second.

[Sniper07]

x3 That's what I have to do with both of my Dodge's and also when putting them into 4wd on the go.

[Scott K]

It could have a bad shift motor om it, if it starts working, keep shifting it back and forth to clean the rust off of the cantacts.

[backlash 1]

OK.

Shift motor has been replaced already at 12,000mi At that time it just stopped working altogether.

Are these shift motors just junk, or is this common?

[Jeremy airjer W]

There are a lot of them that get replaced. The first thing I do with FORD that won't go into four wheel drive is smack the motor with a hammer. If it starts working it needs a motor. If it doesn't start working I'll start running through the diagnostic steps, and then replace the motor!

[HondaRider07]

It's not a shift motor. It's problably your wheel ends on the front spindle loosing their ability to hold a vacuum. Vacuum is what unlocks your hubs, and no vacuum locks them. It could also be a leak in the lines supplying the hubs vacuum or a faulty 4x4 solenoid under the hood mounted the the firewall. I've seen all of these cause this problem.

[backlash 1]

$670.00 later I got the truck back. They replaced a wheel hub, actuator, and selenoid.