i havce a bit of a problem, i have a 97 f150 4.6L. for some reason, the 4wd has decided to stop working for me. i turned on the truck, switched it into 4wd, went underthe truck, and the front driveshaft IS locked in and doesnt turn. but when i start to drive, 4wd doesnt kick in. i talked to my buddies dad who is a mechanic, he thought it might just be the ground wire to the front diff. what do you guys think? its getting embarassing when i get stuck in my lawn on wet days! any help woud b great

 

Park in the driveway? (sorry..couldnt help it)


He is in the right area. I take it then you have electronic shift for the 4x4. Check the wiring to make sure all is good. Look for loose wiring and then check the the t-case motor itself that engages the 4x4. Could be it just needs a good cleaning or a good whack depending on how long it has been since used. Could just be stuck.

 

The front diff is vacuum operated, not electrical. If the front driveshaft is locked up the switch is working, otherwise the transfer case would not have locked the front driveshaft. Look for the vacuum motor on the front diff not working, a vacuum leak on the lines from the solenoids to the front diff, or a bad solenoid for locking the front diff. These solenoids are on the firewall, passenger side up close to the hood hinge. One engages the front diff, the other disengages the front diff. Don't remember which is which. When I had the problem on my 98, it happened to be a vacuum leak. Solenoids and vacuum motor were fine.

 

i may have found the problem, there is a hanging vacuum line underneath my truck, the end of it looks just like the end that is to the solenoid. but i dont know where it goes. i looked under there for almost an hour and a half, i didnt see anything it could go to. could the other end be ripped off or something. if u dont understand what i am talking about, just ask me

 

The vacuum lines hook up to the vacuum motor on the diff and to the solenoids. The 2 solenoids are high up on the firewall on the passenger side. Easily accessible from under the hood. If what you have hanging is under the vehicle itself near the diff,that is probably where it came loose. If it is hanging back near the firewall, it is either loose from the solenoid, or it split in 2.
Unfortunately I don't have any pictures of the solenoids or diff to show where they attach. Maybe someone else here does..

 

yes, the end is hanging loose from down by the diff. there are already 2 vacuum lines connected to the diff. so this line might be to some other part for the 4wd, i am not sure. i would have looked longer, but it was getting dark, and the mosquitos were eating me alive, one disadvantage on living in MN!

 

but if anyone is absolutely sure where it goes, ill fight the mosquitos just to get it working again, i miss my 4-by.

 

Only thing I can suggest is trace both vacuum lines from the diff and see if both or only one ends up at the solenoids. Other possibility is with this loose vacuum line is that it is causing the vacuum to be low enough not to engage the front diff. I would expect though that you would have other problems if this were the case.

 

still no luck, would it help you if i took a picture of the hose and see if it is actually a vacuum line?

 

I doubt it. To my knowledge the only thing going into and out of the diff were 2 vacuum lines. If these lines are not getting vacuum, the only way to tell is with a vacuum gauge.
Unfortunately, I no longer own a 97-03 F150 to compare to.
Only thing I can suggest is try a dealer you trust.
Sorry I couldn't help more.

 

does anybody else wantto join in on this mystery line, i have no idea where the vacuum line came loose from, but it is strapped together withthe one to the vacuum motor, if that hepls any, i really need some help on this.

 

are you sure that line isn't a vent tube? sorry can't really help i don't have vacuum operated mines all manual.

 

i have a 98 4x4. I have had a few 4x4 problems a bad front diff vacuum solenoid and broken vacuum lines. Post a pic of the hanging line I should be able to identify it

 

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. 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 litle poplar trees i didn't see! the wiring harness is mounted right below the drivers side engine mount. the male end of the wire has a grey outside with 2 holes inside which are red in color, the female end is gray, and is facing the front of the truck. i will try to post a pic of it to be more specific

 

I Really Need Some Help With My 4wd,

Any Electrical Wizzards Out There To Assist Me?

I Went To The Dealership To Ask Them What It Was. They Told Me That W/o Paying For Service, They Couldnt Tell Me What Part I Needed. They Could Have At Least Looked Under My Truck And Told What Part I Needed To Buy!
Any Help Would Be Great
Thanks