4WD Vacuum System
Junior Member
Joined: Sep 2009
Posts: 6
Likes: 0
2003 F150 FX4 Lariat
I know this thread is old, but it has provided some valuable insight to my issue. I was wondering if anyone could give any further pointers as to what direction I should take. As for background, I did have to have the front axle fork thingy replaced about 3-3.5 years ago b/c it had broken off. I don't use 4wd that often, but about a year ago I tried to engage it and it did not react at all. No dash lights, no sounds, just nothing. The lights to come on during the startup test (4x4 and Low Range) when the ignition is turned on.
Today after reading the this thread I checked at the solenoids and when I pulled off the lines from the solenoids with the truck running I did have sucking from the top nipple on the 2wd side. When I turned the ESOF switch to 4wd, I still had suction on the 2wd top nipple, but nothing on the 4wd side. I did pull the diaphragm at the transfer case and it seemed to be moving fine when off the truck. I could put my finger over the two nipples and could not push the plunger, but with my finger off it moved freely.
With the diaphragm off, I tried to move the axle fork back and forth and it would only move about .5-.75" left to right. Should it move more than that and should I be able to move it freely with my hand? I sounded like it was hitting something sold within the transfer case house. It definitely didn't move the whole range of movement that the diaphragm plunger would allow.
So fellas, any help? Does it sound like a) a bad 4wd side solenoid, b) bad parts within the engaging mechanisms, c) something in a electrical module or switch, d) combo of one or more above. The truck does have 126,000 miles on it, but 4wd has really only been used sparingly. There would be no reason for the internal parts to fail twice, if that is what it is.
I know this thread is old, but it has provided some valuable insight to my issue. I was wondering if anyone could give any further pointers as to what direction I should take. As for background, I did have to have the front axle fork thingy replaced about 3-3.5 years ago b/c it had broken off. I don't use 4wd that often, but about a year ago I tried to engage it and it did not react at all. No dash lights, no sounds, just nothing. The lights to come on during the startup test (4x4 and Low Range) when the ignition is turned on.
Today after reading the this thread I checked at the solenoids and when I pulled off the lines from the solenoids with the truck running I did have sucking from the top nipple on the 2wd side. When I turned the ESOF switch to 4wd, I still had suction on the 2wd top nipple, but nothing on the 4wd side. I did pull the diaphragm at the transfer case and it seemed to be moving fine when off the truck. I could put my finger over the two nipples and could not push the plunger, but with my finger off it moved freely.
With the diaphragm off, I tried to move the axle fork back and forth and it would only move about .5-.75" left to right. Should it move more than that and should I be able to move it freely with my hand? I sounded like it was hitting something sold within the transfer case house. It definitely didn't move the whole range of movement that the diaphragm plunger would allow.
So fellas, any help? Does it sound like a) a bad 4wd side solenoid, b) bad parts within the engaging mechanisms, c) something in a electrical module or switch, d) combo of one or more above. The truck does have 126,000 miles on it, but 4wd has really only been used sparingly. There would be no reason for the internal parts to fail twice, if that is what it is.
Junior Member
Joined: Dec 2009
Posts: 1
Likes: 0
From: Anchorage
I'm new here, and was hoping I wasn't the only one with this problem! Glad to see something that give more insight than Chilton's or Haynes manuals. I'm gonna tackle this issue in the next few days.
THANK YOU f150online members for the great info and help!
THANK YOU f150online members for the great info and help!
Senior Member
Joined: Aug 2002
Posts: 291
Likes: 0
From: wi
Hey fixed a guys 97 yesterday and the little lever that's on the axle(connected with roll pin) wasn't traveling enough. We took a torch and bent it towards drivers side a little and woolah fixed. So I'd say pull of the axle actuator and try it by hand maybe it's not traveling far enough..
But of course the actuators on firewall(passenger side) are usually the problem.
Jeff
But of course the actuators on firewall(passenger side) are usually the problem.
Jeff
Junior Member
Joined: Dec 2009
Posts: 2
Likes: 0
I have a 06 f 150 4 wheel drive. got a problem with the vaccum on the hubs... there is none. The switch in the dash lights up fine, Checked the vaccum on the IWE solenoid on the passenger side fire wall, when switching back and forth from 4 wheel to 2 wheel and there is no vaccum there either. when the truck is running it should be vaccum on one of the 2 lines i would think, then the IWE would transfer it to the hubs ?? so where is the vaccum reservoir ? and why is there no vaccum on the IWE, either the small line or the bigger one ? Anyone have this problem before ? i been going around for the last 2 weeks stuck in 4 wheel drive because i got no vaccum to disengage the hubs from 4 wheel and my gas mg kinda sucks. Hope someone here can help me. Thanks
Senior Member
Joined: Mar 2001
Posts: 3,248
Likes: 2
From: Rochester, NY, USA
2003 F150 FX4 Lariat
I know this thread is old, but it has provided some valuable insight to my issue. I was wondering if anyone could give any further pointers as to what direction I should take. As for background, I did have to have the front axle fork thingy replaced about 3-3.5 years ago b/c it had broken off. I don't use 4wd that often, but about a year ago I tried to engage it and it did not react at all. No dash lights, no sounds, just nothing. The lights to come on during the startup test (4x4 and Low Range) when the ignition is turned on.
Today after reading the this thread I checked at the solenoids and when I pulled off the lines from the solenoids with the truck running I did have sucking from the top nipple on the 2wd side. When I turned the ESOF switch to 4wd, I still had suction on the 2wd top nipple, but nothing on the 4wd side. I did pull the diaphragm at the transfer case and it seemed to be moving fine when off the truck. I could put my finger over the two nipples and could not push the plunger, but with my finger off it moved freely.
With the diaphragm off, I tried to move the axle fork back and forth and it would only move about .5-.75" left to right. Should it move more than that and should I be able to move it freely with my hand? I sounded like it was hitting something sold within the transfer case house. It definitely didn't move the whole range of movement that the diaphragm plunger would allow.
So fellas, any help? Does it sound like a) a bad 4wd side solenoid, b) bad parts within the engaging mechanisms, c) something in a electrical module or switch, d) combo of one or more above. The truck does have 126,000 miles on it, but 4wd has really only been used sparingly. There would be no reason for the internal parts to fail twice, if that is what it is.
I know this thread is old, but it has provided some valuable insight to my issue. I was wondering if anyone could give any further pointers as to what direction I should take. As for background, I did have to have the front axle fork thingy replaced about 3-3.5 years ago b/c it had broken off. I don't use 4wd that often, but about a year ago I tried to engage it and it did not react at all. No dash lights, no sounds, just nothing. The lights to come on during the startup test (4x4 and Low Range) when the ignition is turned on.
Today after reading the this thread I checked at the solenoids and when I pulled off the lines from the solenoids with the truck running I did have sucking from the top nipple on the 2wd side. When I turned the ESOF switch to 4wd, I still had suction on the 2wd top nipple, but nothing on the 4wd side. I did pull the diaphragm at the transfer case and it seemed to be moving fine when off the truck. I could put my finger over the two nipples and could not push the plunger, but with my finger off it moved freely.
With the diaphragm off, I tried to move the axle fork back and forth and it would only move about .5-.75" left to right. Should it move more than that and should I be able to move it freely with my hand? I sounded like it was hitting something sold within the transfer case house. It definitely didn't move the whole range of movement that the diaphragm plunger would allow.
So fellas, any help? Does it sound like a) a bad 4wd side solenoid, b) bad parts within the engaging mechanisms, c) something in a electrical module or switch, d) combo of one or more above. The truck does have 126,000 miles on it, but 4wd has really only been used sparingly. There would be no reason for the internal parts to fail twice, if that is what it is.
Senior Member
Joined: Dec 2006
Posts: 119
Likes: 1
From: Cali
The number one thing I'd be looking for in your case - expecially given your description of the problem - is the ESOF (Electronic Shift On the Fly) motor. It's located on the back side of your Transfer Case and it has nothing to do with vacuum. It's basically a small electric motor that engages and disengages 4 Hi and 4 Lo in the TC. Since it's located in a nasty area and rarely gets used, it tends to lock up over time. Sometimes you can free it up with a few love taps from a hammer, but if that doesn't work, it's a pretty simple replacement job.
Here's a thread i started about the issue:
https://www.f150online.com/forums/ot...rrelation.html
Could you by chance show a pic of it's location? Is there a specific way to test if it's in proper working order.
I believe my issue is more electrically related rather than vaccum but i may be waaay off as i have very limited experience w/ these 4WD systems.
Thanks also for all the insightful posts in this thread!
Happy New Year!
Senior Member
Joined: Jul 2007
Posts: 186
Likes: 0
From: NC
There are no locking/unlocking HUBS for these trucks. There IS a cable conversion kit for the differential. It's easier/better, IMO, to fix whatever is wrong with your vacuum system and be done with it.
Junior Member
Joined: Sep 2009
Posts: 6
Likes: 0
The number one thing I'd be looking for in your case - expecially given your description of the problem - is the ESOF (Electronic Shift On the Fly) motor. It's located on the back side of your Transfer Case and it has nothing to do with vacuum. It's basically a small electric motor that engages and disengages 4 Hi and 4 Lo in the TC. Since it's located in a nasty area and rarely gets used, it tends to lock up over time. Sometimes you can free it up with a few love taps from a hammer, but if that doesn't work, it's a pretty simple replacement job.
You were dead on. Thanks for the help. I went out a few days ago and unhooked the wiring harness, blew it out and plugged it back in. I then tapped on the motor a few times. Got back in the truck and turned the switch and it started clicking. Flip the switch a couple more times and bam, 4x4 high engaged. It took a little while, but I then got low to engage after it got hung up in neutral for a few minutes (I thought oh ****, what did I do now), but all of a sudden it clunked in. I have tested it out everytime I get in the truck to make sure it still engages. I guess I didn't use it enough and it just got frozen from being ignored. I guess worst case I know what the culprit is and can replace it for around $100 and a few minutes of my time if it craps out gain.
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Not sure if this was mentioned yet, so -
NOTE: To those who are unaware. The Ford actuator line connect is backwards and wrong, going from Ford Service/workshop diagram for certain model years. The Blue and Pink are switched. Make sure you document/write it down somewhere before you disconnect to test/service actuator @ the front axle, IF you plan on using another information resource when reconnecting.
NOTE: To those who are unaware. The Ford actuator line connect is backwards and wrong, going from Ford Service/workshop diagram for certain model years. The Blue and Pink are switched. Make sure you document/write it down somewhere before you disconnect to test/service actuator @ the front axle, IF you plan on using another information resource when reconnecting.
