Update: the non-engaging 4wd is fixed!!!!!!!!
<HR style="BACKGROUND-COLOR: #d1d1e1; COLOR: #d1d1e1" SIZE=1><!-- / icon and title --><!-- message -->First I want to thank all who contributed to my resolving my 4x4 engagement problem, especially Alloro, Denphillips2, and Jennkent5454, and StevenIll. Each of you were integral in assisting in resolving this issue.

You can read my posts and follow the plan of attack. At first I thought this was a t/c motor issue. I replaced the motor and nothing changed. Upon further reading on this site, I was directed to the 4x4 actuator and the vacuum lines connected thereto.

What was most helpful was getting under the truck. I first checked around the actuator, sprayed it with WD-40 to ensure movement. I had a friend get in the truck and change the ESOF switch from 2 to 4wd as I watched the acutator. It would only move one way which led me to believe I had a vacuum issue up the line. To be sure, I began by disconnecting the vacuum lines to the 4x4 actuator. I found that I had vacuum to the red line (4x2), but novacuum from the blue (4x4) If that was the case I was told to move back up the vacuum lines to look for a crack or listen for suction. Part of the difficulty in locating such a crack or leak is both the red and blue lines which come out of the solenoids are protected and hidden in that black flexible conduit so how do you know if there is a problem without pulling it off?

Anyway, I was told to focus on areas near the battery where the solenoids are located due to battery acid and cable movement so I started there and just moved down. I did peel some of the conduit back in an area that looked corroded and suspicious and don't you know, I found it! A hole in the blue (4x4) line! It appears it was due to battery acid. Glegarry Auto Parts in Livonia, MI "gave" me a piece of vacuum line as a Christmas present which I bridged over the cut-out portion. I added a little caulk adhesive to hold it in place and my 4x4 works again! YEAH!!!!!!

Note: As I have always had, my A4wd light still blinks and I don't know why. Perhaps I'll deal with that next spring. BUt 4x4 hi and low are functioning

Thanks again, all. Have a very Merry Christmas and Happy New Year.
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Update: the non-engaging 4wd is fixed!!!!!!!!
<HR style="BACKGROUND-COLOR: #d1d1e1; COLOR: #d1d1e1" SIZE=1 itxtvisited="1"><!-- / icon and title --><!-- message -->First I want to thank all who contributed to my resolving my 4x4 engagement problem, especially Alloro, Denphillips2, and Jennkent5454, and StevenIll. Each of you were integral in assisting in resolving this issue.

You can read my posts and follow the plan of attack. At first I thought this was a t/c motor issue. I replaced the motor and nothing changed. Upon further reading on this site, I was directed to the 4x4 actuator and the vacuum lines connected thereto.

What was most helpful was getting under the truck. I first checked around the actuator, sprayed it with WD-40 to ensure movement. I had a friend get in the truck and change the ESOF switch from 2 to 4wd as I watched the acutator. It would only move one way which led me to believe I had a vacuum issue up the line. To be sure, I began by disconnecting the vacuum lines to the 4x4 actuator. I found that I had vacuum to the red line (4x2), but novacuum from the blue (4x4) If that was the case I was told to move back up the vacuum lines to look for a crack or listen for suction. Part of the difficulty in locating such a crack or leak is both the red and blue lines which come out of the solenoids are protected and hidden in that black flexible conduit so how do you know if there is a problem without pulling it off?

Anyway, I was told to focus on areas near the battery where the solenoids are located due to battery acid and cable movement so I started there and just moved down. I did peel some of the conduit back in an area that looked corroded and suspicious and don't you know, I found it! A hole in the blue (4x4) line! It appears it was due to battery acid. Glegarry Auto Parts in Livonia, MI "gave" me a piece of vacuum line as a Christmas present which I bridged over the cut-out portion. I added a little caulk adhesive to hold it in place and my 4x4 works again! YEAH!!!!!!

Note: As I have always had, my A4wd light still blinks and I don't know why. Perhaps I'll deal with that next spring. BUt 4x4 hi and low are functioning

Thanks again, all. Have a very Merry Christmas and Happy New Year.

 

Golfover--glad yours is working. took truck to oil change shop and had the guy flip the switch while I was watching my new actuator. Nothing moved at all. took off vacuum lines and found vacuum in the pink line only. I will follow black line now for rips, but hoping it is the solenoid not working. Does anyone know what the solenoids should read if I put a tester on each pin? I could not find this in my manual.

 

Hey Wrongwrench,

I wish you the best in locating the problem. It sounds just like what I experienced. Frankly, I'm surprised I found the damaged area. Getting up on a ladder and using a real bright light helped to see. Because these trucks are so loud I don't think I would have ever heard the leak.

Also, don't be afraid of peeling back and looking inside that black conduit. I know in the past I used to have a battery which the terminals became really corroded. I used to clean them off with baking soda and I bet dollars to donuts this contributed to my issue. Chances are real high you'll find it.

I don't know what the test is on the solenoid or line but I was told its not that great. Alloro was real instrumental in assisting me so he may not be a bad person to contact.

 

thank you for your reply----I will check the black line first with truck running. if no leaks, then it has to be the solenoid I would hope? I read somewhere that the solenoid should give a 12V reading across when it is engaged. However, can't one test resistance across the poles on this too?

Unless someone has other ideas, fire away. I am taking my time as I have another truck to drive.

 

Wrongwrench,

I'm not sure if this nugget is helpful because it deals with the IWE, which is the newer system used to lock hubs, but I'll pass it to you just the same.

https://www.ford-trucks.com/forums/8...then-some.html

 

This one hasnt been easy diagnosing. I took both vacuum lines off and feel a suction on each of them in the lower holes. I tried my meter for resistance and found a reading of 66.6 on both solenoids? Cant see any tears or rips in the lines and the new actuator still doesnt move. I put a new transfer motor on as well and now know that wasnt the issue. I broke an ear off the solenoid connector so hopefully that will stay on. Starting to get frustrated and mad as everyone else on the forum seemed to fix theirs. I might have to take this to a dealer with tail between legs and dunce cap on if I can't figure this out.

 

WW, I feel your frustration. I don't know if you read this on answers to my issue or you already knew this, but Alloro sent me this regarding vacuum (suction) in both lines at the actuator:

Quote:
<TABLE border=0 cellSpacing=0 cellPadding=6 width="100%" itxtvisited="1"><TBODY itxtvisited="1"><TR itxtvisited="1"><TD style="BORDER-BOTTOM: 1px inset; BORDER-LEFT: 1px inset; BORDER-TOP: 1px inset; BORDER-RIGHT: 1px inset" class=alt2 itxtvisited="1">Originally Posted by Golflover
is it safe to say if there is no vacuum in the hose at the actuator when I pull the line then an actuator replacement will more than likely to resolve the issue? And if I do have vacuum at the actuator then where should I look as the problem; the selector switch? Or is that the least likely possibility?
</TD></TR></TBODY></TABLE>
If there IS vacuum at the actuator hose then replace the actuator, because it means the actuator isn't responding to the presence of vacuum. If there is NOT vacuum at the actuator hose, then you'll have to follow the vacuum line back and test for vacuum at every junction or component you run into to see where you start getting vacuum.

Like anything, perhaps your actuator had a short life. I had a new fuel pump that lasted 5 months once. Or, it's frozen. Can you manually actualte the arm after spraying it with WD 40?

 

When I bought the new actuator, I pulled the arm back and forth to make sure it worked. I have asked on the forum what the stroke measurement is for the fork on the differential. How much should that move?

I just wish I knew how to test the solenoids for resistance. Took battery out and put testors to both pins, they read the same if 66.6 is a reading??? I have plenty of vacuum on both lines, actuator I know works, guess I should just buy new solenoids. If that doesnt do the trick, then I don't have a clue.

I like these forums, but it also tells me the many problems people have with their vechiles. I hope some day we can build something and put a 10 year 100,000 mile warranty on USA products. Just looking over the threads on the newer trucks makes one think we still have a ways to go for long term truck quality.

 

Thanks for the write-up boys. My 4WD failed me when I needed it most. We had a big blizzard here in SE Wisconsin a few days ago and my wife got stuck at the bottom of our slightly inclined street with her car in about 12-15 inches of snow, at midnight no-less. No plows out......they were waiting out the blizzard. I was going to attempt to pull her up the street and I couldn't even get my truck out of the driveway (large drifts) and I discovered I had no 4WD!

Anyway, I worked on the truck today. I had vacuum from both lines at my 4WD actuator, but no movement from the actuator. I ended up working it by hand and spraying the piston with WD-40 a bunch of times and eventually got it moving somewhat freely. I put things back together and she's engaging into 4WD fine now. If it happens again I will just buy a new actuator, but for now it's working fine.

Thanks again for taking the time to write things up...........very helpful.

 

where might a guy find something like this?

 

F250 4x4 1998 4.6L
I'm having a related problem up for comment. I initially couldn't get air from my dash.
I replaced my actuator after reading this was the cause, before I read about checking vacuum lines. I didn't have 4x4, high or low, but now I do. I watched the actuator lever move, my front axal turns, 4x4 light on dash comes on, solenoids click, etc.
I still do not have air to my dash and only to the defrost vents.
Does this sound like a very small vacuume leak? Which line, red or blue, would you guess?
I priced the Mightymax, $40.
Wouldn't it make more since to just replace the vacuum lines which cost about $.59 a foot?
Thank you for your response.

 

Baseline 4x4 PSL750, 4x4 Posi-Lok Vacuum Actuator Eliminator Kit, Adapters and Brackets

 

The defrost position is the default position when you don't have vacuum to the system. Check the line that runs through the firewall back behind your battery. I think you'll find the problem. This is frequently the problem.

 

Thanks, I'll have some time in the AM tomorrow and I'll take a look. Thinking about that is on the other side of that firewall is scary. Will have to disassemble the whole inside dash?