I am having a problem with my 1998 F150 4x4. The 4WD is not engaging. It is a manual shift. I have checked the transfer case by turning the drive shaft in 2WD it is free. When I shift into 4WD it is does not spin freely. So I believe that is OK. I have checked the vaccum diaphram. It will move the piston when I attach a hose and pull vacuum on the inboard hose barb. So I believe the diaphram it self is OK. I am not sure if the hoses and selenoids are OK. They look fine. However there is a constant vacuum on the inboard hose line (red/pink color) wether I am in 4WD or not. Is this OK? How can I check the selenoids. If all this is OK, the next thing I believ it could be is the shift fork in the differential. Is that a difficult job? Do you need to pull the whole axle out to replace it?

Thanks for your help.

 

I had a problem with the shift fork I had to replace it. There is a peice of teflon on the end of the fork and it had come out, so the fork was loose on the slider gear and it would not move it far enough. I took the diff out to replace mind its not a big job. Once you have the diff on your bench remove the right tube and every thing is right there. Some people do it with out removing the diff. My truck is a 1998 F150.

 

I just did the front gears on my 97 and belive me, it is much easier to work on with the diff. out. It is very easy to get out and does not wiegh very much. There are only three main bolts and then the driveshaft and cv halfshafts. My 4 wheel drive is not working right now either. But that is because my wife dicided that she was a wheeling queen and blew up the cv halfshaft on the passenger side.

 

If your dash 4x4 indicator does not light up when you shift, a switch on the transfer case may be bad. Mine was intermittent for awhile then died completely, not much fun during a Maine winter. It is a three position switch, off, 4 high, and 4 low, and is located near the shifter shaft. It switches the dash lights as well as the vacuum solenoids for the front end. Good luck, RideUs60.

 

I have the same problem with my 2000, The local ford folks gave me an oil pressure switch to replace on the transfer case. I know where this is located but it doesn't sound like the right switch. Can anyone confirm that this is the right switch and if not please let me know where the switch is I need to replace.

Thanks

Jeff

 

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i have a 4wd problem, i found a wire hanging down under my truck. i believe it is an electrical line from the tranny to the front diff. the wire is tied together with the vacuum line that goes to the vacuum motor on the front diff. when i say tied, i mean zip tied, not spliced. i looked at where i think it goes (unsure of what i see), and it looks like it broke clean off the tranny and broke the harness. it was probally ripped off by the little poplar trees i didn't see! the wiring harness is mounted right below the drivers side engine mount. the male end of that plugs into the harness has a grey outside with 2 holes inside which are red in color, the harness end is gray, and is facing the front of the truck.
i ANY ONE has any idesa of what part this is, i will be very greatful. i would sure hate to not have 4wd in a minnesota winter.

 

im sorry, the line does not go from the tranny to the front diff., i believe it comes from the solenoid on the firewall.

 

Hi i have a 97 f150 with the 4.6ltr in it. My 4x4 is not working either. It is stuck in 4 low but i did work in 4 high until i turned the switch. Now it wont come out of 4 low but all 4 wheels are engaged. The light on the dash does not come on either. I took the "gem" module out from underneithe the dash and cleaned it also all the connectors that i could find. I also put a new switch in the dash. Sounds like a relay could be bad but i dont know where they are at or how many of them there are. If anyone could give me a clue on where or what else 2 check i would greatly appreciate it thanks
Louie

 

Hi Louie,

I assume you have the transmission in neutral and your foot on the brakes when you try to switch it? Lots of people don't realize that has to be done.
If you're doing that right I would have someone sit inside the truck with their foot on the brake, transmission in neutral while you tap gently on the motor on the transfer case. Sometimes the contacts inside the motor get dirty or whatever the motor won't turn to shift the transfer case.

 

Thanks Dave yea i do have my foot on the brake and the truck is in neutral. I did take the motor and assembly apart and cleaned the brushes on the motor. And everything seemed to be ok inside of the motor. When i first bought the truck it was in 2 hi and then i got it to go into 4 low but it wont come out of 4 low. I am leaning twards a gem module because when i took it apart i did notice some water damage on the circuit board. So i thought that mite be the problem but i dont want to spend the money for something that isnt gunna fix it. So im still not sure what is wrong but im up for offers. Thanks again
Louie

 

The GEM doesn't like water in it.
Is there an autowrecker there that you could get a GEM from rather than buy a new one?
You could take it into your dealer and have it scanned for codes. That would probably be the best way to diagnose it rather than just throwing parts at it.

 

I've had trouble with my 4 wheel drive not working in the past.all it needed was a little w-d 40 sprayed on the shaft going into the front differential and worked in and out a few times. Now, everytime I change my engine oil I give it a shot of w-d 40 since I'm right there. haven't had any trouble since.

 

Hey JBWASH, what exactly are you spraying with WD40?

 

The shaft coming out of the front of the diff. conected to the vacume canister. Remove the plastic cover that protects the vacume modulator and spray all the pivot points.These pivot points don't seem to tolerate getting dry. A few of my coworkers had the same problem and it worked for them. I found out my 4x4 wasn't working the hard way.Had to get a pull.An ounce of prevention is worth a pound of pull.( The guy who pulled me out was driving a dodge.)