Wife was driving the Ex the other day and it was fairly icy (packed snow). She told me " I think the tires are not that great in the snow", " I had to take a few runs at a hill and it was slipping a lot". Oh, and also it seems like the defroster comes on when I turn on the four wheel drive... So that tells me there is a vacuum leak correct?

I started up the Ex and played with the 4x4 (ESOF) system after reading a few threads about it, heres what I came up with. I can engage the High range with the dial on the dash and hear a "thunk" of the transfer case and the light on the dash comes on as well. Put the gear selector in N, and switch to Low range and hear yet another "thud" from the transfer case and 4x4low indicator also comes on. Wife was right, the blower does revert from Face to defroster in doing this.

In both 4x4 high/low I drove around in some tight circles in the dirt to listen for binding in the front axle I dont think I can hear any? Stop, go in to Park, set E-brake and kneel under the front end and I can not turn the axles on either side by hand while in 4x4, they seem to be locked in. Switch out of 4x4 and go again and do the same test, this time I can turn the passenger side axle freely, but the Driver side still appears to be locked in, and can not turn the axle? Bad hub? Bearing? vacuum leak somewhere not unlocking? I want to trouble shoot this today and need it working as we have a road trip over the Mts. for the holidays in a few days, reeeeeaaaly want/need 4x4. I did notice in driving it into work that it is pulling a little to the left, and I dont remember it doing that before.

Thanks in advance for any assistance!

 

Yes, it does. Focus on checking the PVH solenoid for vacuum leaks, it's really common for them to leak.

https://www.google.com/search?q=f250...w=1920&bih=961

 

Gotcha, thank I will take a look at it. I was just out playing with 4x4 ESOF, I switched it on while the Ex jsut had the key in the ON position and I did not start the truck, I wanted to listen for the pump running, It is defiently running, but when I switched it from 4x4 to 2x4, the pump continued to run? So I started the truck and drove it for a few minutes and the pump finally turned off...

 

So was able to isolate the issue by working backwards from the hubs (if anybody gives a rip) used a vacuum pump to pull 15lbs of pressure at the hub and no leak at the hubs. Then hooked the gauge to the pump end of the line, and it pulled no vacuum on the driver side. Pulled a vacuum between pump an hubs and still no leak down. Long story short, R&R the PVH solenoid and all is well, thanks Sho89! 2nd easiest job so far next to rear hatch struts.

I am super impressed with the 4x4 on these rigs, lot of pull and minimal slippage, not sure it was ever functioning at 100%. As a caveat to that, these rigs actually do really well in 2x4 in the snow, must be the shear weight unlike a truck with an empty bed!

 

Thanks for the update. Reps.