Just as everything seemed to be going decent with the truck, the ESOF decides to rear it's uglyness. Had a decent snowstorm yesterday, I was driving home from work in 4WD all was good until I got about half way home. I realized something was wrong when the backend decided it wanted to lead. The 4x4 light was on but the hubs weren't locked. Made it home and started to search and read. Had to work today so I locked the hubs until I could dig into it. I just need to verify what I saw and what I need to replace

The vacuum pump does run, cycles and shuts off. From this picture I assumed the hub line is the one leading toward the engine, the other is going toward the firewall for heater controls


I hooked a vacuum pump to the hub line. Pumped to 15 and it held. Stayed that way for 10 minutes and should stay even longer. I'm assuming this test means the hubs are good.


So, after all this, does that mean that this part is going bad? I forget the name of the part but based on all my reading I think this may be the problem.


Thanks for the help

Fred

 

That looks like the PVH solenoid and yes it can cause issue with the ESOF system.

 

You also need to check all your fuses in the box under the hood right beside the master cylinder. I had just bought that ESOF valve myself. It's your likely problem, knowing your pump works, shuts off at full vacuum, and the hits hold air. Verify also that ipthe valve is getting power when you change the switch, cause a simple fuse issue can look like the valve is at fault. Possibly also verify your transfer case, but it sounds like your in 4*4 is working with hi pubs locked. Here are some other threads showing the fuse box under hood and gives you what they all are. Do a. Search on ESOF.

 

https://www.ford-trucks.com/forums/p...ctureid=104425

Compliments of another post.

 

Ps. Another thing to check, there is a set of hoses, it connects to the reserve tank, over to the HVAC and the ESOF valve. Mine had a pin hole in it on the ESOF actuation side. Had to buy the whole thing.

 

Im thinking you may have checked the Wrong Line???

Was the one you were On going to the Heater Vac Control on the Supply line for Heater

It starts with a Pump then Tank then 4X4 Control silinoid then to Hubs


Your LAST Pic is the 4x4 Control Silinoid But Make sure you check the Hub Line Maybe you did and Im Lost Just double checking

 

Read this it has the VAC Line Diagram and theory of operation

4x4 PDF

https://www.ford-trucks.com/forums/a...0&d=1297450348

 

The line I was on was disconnected from the line that goes to the control solenoid. I assumed by the direction it was heading that it was for the hubs, the other line headed right to the firewall so again I guessed that it was for the heater controls.

 

The 2 Vac lines in your First Pic go to the HEATER Control BOTH


My 4x4 vac line to the Hubs is more to front

 

Thanks for the link. Looks like I may have tested the hub line through the control solenoid. I have to retest and sort out the lines again. No fun when its 15 degrees out there. I should just lock the hubs and wait til warm weather.

 

I started to write that and my computer Died

I thought that's might be what you did

It may have worked if the Switch in cab was at the right setting it also Vents so Timing would play into that I believe its all in that PDF

If you test after the silinoid you should be golden

 

This may be helpful if you need to test the solenoid functionality.

mchan68 Quote: This is the PVH (Pulse Vacuum Hub) solenoid. Disconnect the three wire connector to it. Turn the ignition key to the RUN position. Get out your DVOM and set it to DC-VOLTS. Check the middle wire (light blue with pinkstripe), by probing it with the red lead and connecting the black lead to your passenger side battery ground. You should see 12 volts approximately. If you're not getting 12 volts there, you'll need to check fuse #27 (15A) on the fuse panel inside the truck under the steering column, for an open circuit. If the above checks out good, reconnect the three wire connector back onto the solenoid. With the ignition key in the RUN position, connect a jumper wire or paper clip into the back side of the red wire and jump it to the passenger side battery ground terminal to test the hub DISENGAGE circuit. You should hear a click from the solenoid as you do this. Now repeat this same test on the grey with black stripe coloured wire to test the ENGAGE circuit. If you don't hear clicks from the solenoid while testing either, or both circuits, replace the PVH solenoid. The part number for the PVH solenoid is 7C3Z-9H465-A. The price of this part is as follows:

 

Thank you Shane

 

Thank you very much. If it ever decides to warm up I'll give a run through.

 

I took a quick look at it this morning and I see that I got things mixed up. Once it warms up I'll try this again.

Thanks