My 97 Exp. 4wd isn't working. I have all the lights on the dash switch, 2wd, a4wd, 4wd, etc. I've seen posts where folks have talked of cleaning excess grease out of a switch. Is this dashboard selector switch the one they are referring to?

I tested the vacuum motor on the front axle; applied 10" vacuum to the motor, and it bled off quickly (45 sec). Also the motor shaft only had about half the travel of the new one I got from Ford. Figured I found the problem.............nope, something is still wrong!
I tested the vacuum lines at the motor. With the selector switch set to 2wd, I removed the pink line at the vac. motor and read 17" of vacuum. Doing the same test on the blue line, with the switch set to 4wd, I had 7" of vacuum. This doesn't sound right to me.

With the vacuum motor removed from the front axle, can anyone tell me just how easy the shift lever going into the front axle should move? Mine is pretty stiff. Seems like a lot for a vacuum motor to move.

I can see where the two vacuum lines run up past the right side (passenger side) of the motor. It looks like they join up with other lines coming down from the manifold. There looks to be an electrical connector bundled with them. It is difficult to see this stuff from above, access is blocked by hoses, battery. I'm thinking of removing the inner wheel well for better access as I am concerned that there may be a leak there.

Can someone please send me some ideas, maybe some typical problems associated with this system. Are there other solenoids, switches to look at? Thanks for the help!

 

Larry,

My name is Chee and I too am experiencing problems with my 97 Expedition four wheel drive. All my dash lights work and the unit engages at the transmissioin when applicable, but the front wheels do not engage.
Have you solved your problem yet? If so, can you reply to this message with your solutions?


Thank you,
Chee.

 

Yes, my problem is fixed! Here is what I found. First, the reason the motor only had half the travel it should is that there was a burr on the shaft. Since I had already purchased a new motor from Ford, I installed it ($160). I replaced the connectors at the ends of the vacuum lines at the motor, as one was a loose fit. I then started the engine and tested for proper motor operation, which was negative! I got the vacuum guage out again and tested the lines at the motor--they read less vacuum than before, with even the pink 2wd line reading low vacuum. I then started tracing vacuum lines. I found my problem at a location inside the right wheelwell, below the battery. There is a connector there - mine was very difficult to reach w/o removing the inner wheelwell, battery, etc, but I was able to pull it into view at the lower edge of the wheelwell. What a mess! The connector was mostly separated, and caked with road grime. I pulled it apart and gave it a good bath with brake cleaner and a toothbrush. I re-assembled it and lashed it together with a plastic tie. Re-checking the vacuum, I now have a very solid 20" on both lines! The motor tested good, and the 4wd is now working fine. I intend to go back when I have more time and improve this vacuum connector; maybe change to a different one, or install heat-shrink tubing over it. Incidentally, the operation of the motor is for it to pull the plunger IN for 4wd, and OUT for 2wd.

 

Larry,

Thank you so much for your input. I will get working on my 4X4 unit this weekend.

Thanks again,
Chee.

 

Hey Larry, I read up your fix. I am having the same issue on my 98. However my line going from the solenoid to the hubs are broken, I am thinking of just replacing the whole tubing. Do you know the dimension (diameter) of this hard thin plastic tube? or can we replace it with some rubber hose ?
Thanks in advance

 

You can, you just need to know the diameter of the 2 end fittings and the length. Then go and buy the correct size vacuum tubing at the auto parts store.

 

is there a standard size ? or each year was a different diameter ?

 

There could be a standard size but someone would need access to many model years to be able to verify that. Your only guarantee is to check the size on yours for yourself.