2005 4.6 f150 4WD drive is not engaging.the front pass.wheel makes a grinding noise while in 2WD.when i shift to 4WD the noise goes away but 4WD does not engage. solenoid? actuator? or something more?

It sounds like you have different size tires on the front than on the back causing the t-case to bind up. If not, your having an engagement/disengagement issue in the t-case or the shift actuator for the t-case

may be just a stupid solenoid!

You probably have a front drive splined disconnect assembly that has gone bad. This assembly engages the front differential when 4WD is selected. Below is a figure of the item, it is on the passenger side of the differential area.

Hello, It would not hurt to check and would cost you nothing to do so. The valving controlling the vacuum to the actuators could be giving you partial engagement. But if only on one side is doing it, I would think it would pull to the passenger side when in 2 wheel drive.

I had a client with a similar noise and on his truck the front driveshaft had a bad u-joint. Because the driveshaft is to your right, at the center of the truck; he also blamed the passengers wheel. You get a lot of sympathetic motion in the drivetrain. If you think about it, wear can occur on one side of the u-joint. When the shaft is being dragged along by sympathetic motion the driveshaft is being pulled, but when you hit 4x4, now the shaft is pushing and the pressure shifts to the opposite side of the u-joint. Under pressure the joint is now tight.

You may observe rust and grease "tracking" in the areas of the U-joint when you check the front driveshaft. I hope my solution is very helpful in solving your problem. Would appreciate a note when you find the cause of this problem.

Not good! there is a sensor in your transfer case that senses that you are now in four wheel drive if your transfer case does not lock in it will set a code and the light will flash and default back to two wheel drive. check the fluid level in the transfer case and front differential for a sign of internal failure. that is causing the grinding sound.

Hello, Sounds like you've got a bad wheel bearing there or a bad 4X4 hub there. You should have that looked at immediately as the unit in question will seize up at anytime. The usual way the noise goes is it will get louder & louder, then quiet down, then that wheel will just seize up & lock up solid. Try feeling the center of the wheel after driving it and you will find it to be very hot (hot enough to make water steam). Please replace the unit soon before you regret it. Good Luck!

ASE mechanic here:
check the king pins in the front end and the u joints for any kind of play. sounds like front end play while four wheel drive is engaged and stills is affected for a while when two wheel drive is activated. this year truck most definitely has a manual four wheel linkage that could be the problem too. try lubing up any moving linkage and i would shift it in neutral. keep me posted

front hubs need replaceing or greased. maybe front dif needs fluid.

Hi Terrell,

First off, thanks for the detailed description of your problem. I wish they were all as well written as yours.

It's tough not being able to hear the noise it's making. Luckily I can draw parallels to my own experiences with GC's. Mine has 'Select-Trac', which like your 'Command-Trac', enables us to shift on the fly to 4WD. Meaning, we don't have to stop, get out, lock the hubs, get back in then shift to 4WD. Also like yours, my front end was making some noise.

What was up with mine: The 'Select-Trac' on my G.C. is a lever type switch on the center console. When I switch from 2WD to 4WD it routes a vacuum line to an actuator which engages the transfer case. The moving parts are all near the T-Case. While in 4WD, going any faster than a crawl I'd hear a mild grinding/whirring sound. It increased with speed, all but disappeared as I decelerated and made me crazy.

What it turned out to be was a Vacuum leak. The 'bellows' (for lack of a better description) type actuator was only partially engaging the the 4WD. Enough to lock the drive train, not enough to fully mesh the gears resulting in all sorts of worrisome noises. I found and fixed the leak, adjusted the range on the mode rod and that was it.

You're thinking, 'That's special'.

Well here's the parallel.
Command-Trac is also vacuum actuated. The difference is it engages your hubs from the the front axle by means of a 'shift fork'. The technical name is the 'Command-Trac Axle Shift Motor'.
When applied, the vacuum actuator moves the fork one way or the other, engaging or disengaging the hubs.

From your excellent diagnosis, it sounds like 4WD isn't fully disengaging.
You were correct about the front drive shaft. It should not be spinning while in 2WD.

Qualifiers: Is the grinding sound different at low speeds? While making sharp turns?

Have another look with these new facts in mind. Check vacuum lines, lubricant in the axle.

If you get me your engine size, tranny type, etc. I can probably scare up some vacuum diagrams (on the off chance you need them).

I hope this opens new doors for you.
Comment me back with what you come up with.
Good luck buddy.
Mike

My 2003 F150 Supercrew would not engage in 4x4, it ended up being the shifting fork in the front end, cost me $200.