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February, 7, 2007 AT 7:14 PM

My 03 FX-4 5.4L Supercrew has a problem. There are no error codes thrown.

Transfer case seems to engage just fine and the dash lights indicate that the system is engaged. There are no problems engaging 2H, 4H, or 4L. Except that once in awhile the front axle either mysteriously disengages or won't engage. And when this happens the system will not engage again until the truck has made a couple of tight turns on dry pavement. Which isn't always available obviously!

In the snow the 4WD only works about 95% of the time. I think that I isolated the problem to the front axle ESOF vacuum control solenoids and/or actuator this week, and $200 spent at the dealership to diagnose it says that there is " muck" (that was the term given) inside the vacuum system and they want to replace both solenoids and the actuator. However these items all three pass all of the Helm manual tests for voltage, resistance, and function while on the lift and I cannot hear see or feel anything like " muck" inside the system.

Today, I drove it for two hours on snow covered fire roads and it worked fine. Except twice. Two times the system failed to go from 2WD back into 4WD (but the dash lights indicated that the transfer case was engaged) and continued to refuse to turn over the front wheels until I finally exited to bare pavement and did a couple of hard turns, at which point the axle then dropped into 4WD just fine.

Any ideas on what this might be? I thought maybe it was a vacuum leak on the 4WD solenoid side of the system but all connections look good. If it is a vacuum loss it would have to be sporadic, which doesn't make much sense either.

I've now flushed the front axle oil twice with Mobil 1 75w90 synthetic, once at 30k miles and now again at 52k miles. There are no odd noises.

The problem has existed the whole time I have owned the truck which has been two years and 25k miles. Fortunately it doesn't snow all that much here.

I'm stumped.


4 Wheel Drive


5 Answers



February, 7, 2007 AT 7:20 PM

You might have the hubs them selves checked out, it sounds like one of them are engaging and disengaging.



February, 7, 2007 AT 7:32 PM

The system doesn't have locking hubs, only the axle locks and unlocks by way of a small lever shaft that is moved about 20 degrees back and forth by the vacuum driven axle mounted actuator.

The half-shafts are both permanently fixed to each wheel by way of CV joints.

One thing that I have not done is to remove the actuator guard, mark the 2wd and 4wd positions with a crayon, drive it without the guard and then crawl underneath and look when it stops working out on the trail to see where the actuator is holding the lever.

Another possibility is that the system just doesn't like to engage when all four wheels are on a slippery surface. But that isn't the case with my 2006 Expedition.



February, 7, 2007 AT 7:53 PM

You know the prolem might be the part in the axle that the act, is hooked to there should be a small fork that is around a coller that slides back and forth to engage the fwd, and it only locks the one side when it engages so that part might not be working right.



December, 9, 2008 AT 3:07 PM

I also have a 2003 F150 Supercrew with the same symptoms. No 4x4 until several sharp turns on dry pavement. Have you found a solution to your problem?



February, 14, 2009 AT 7:00 PM

I also have a 2003 F150 Supercrew that has intermitent 4wd. I had the computer module replaced for around 400 bucks but that didn't do the trick. I can hear the 4wd kicking in and out as I drive down the road. Any additional insight into this problem would be greatly appreciated.

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