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Jerry,

The solenoid might not be the correct term so let me try to explain the manifold assembly a little better.

The assembly consists of five (four on older coaches) solenoid valves mounted on a purpose built manifold.

From the top down you start with a solenoid coil held in place with a snap ring. If you remove the snap ring the solenoid coil will slide off the “stem” of the valve. The electrical wires that energize the coil are in a connector that is held in place on the coil with a screw. It is important to understand the location of the wires is specific to the position on the manifold assembly. In other words don’t move the electrical connector from one position to another.

Once the coil has been removed from the valve the valve itself can be removed from the manifold by removing two screws. I have seen some screws with a phillips head, others with a torx.

Use caution removing the valve body from the manifold because beneath the valve will be two O rings. The O rings sit in a groove in the manifold. Don’t lose them.

Almost all the time if there is a problem, such as the coach not returning to the driving height after being leveled in a campground it is a failed solenoid valve coil. That means all that has to be replaced is usually the coil. In an emergency any other coil from the manifold will work to get you going as long as all the coils in the stack are the same voltage as the center coil. The center coil is the only one energized when in the driving position.

I hope that is a better explaination.

[Peter]

Jerry,

When apart, they look like this:

[Jerry]

Jerry,

Your loss of air on both sides in the rear is not related to the solenoid valve manifold, but I am still puzzled as to why it is happening.

The purpose of the solenoid valve manifold is to convert the electrical signal of the level low (and HWH) controls into a pneumatic signal. The drive position on the level low control (called the “road” position on a Liberty) energizes the center solenoid valve coil when the key is on. That opens the center solenoid valve and it send air pressure to all three 5 port Norgren valves on your coach. That air pressure pushes the Norgren valve spool to open the passageway between supply auxiliary air pressure and the ride height valves.

The ride height valves will then either exhaust air to lower the coach or add air to raise the coach to their respective air bags. As soon as you turn the key off the solenoid valve closes, air within that circuit is exhausted and the 5 port Norgren valve spools return to the neutral position and shut off any air flow to or from the air bags.

Let’s analyze what happens if the center solenoid valve leaks. The answer is …..nothing.

That is not quite correct. But close. If the solenoid valve leaks (center valve only) the pilot pneumatic air lines are pressurized and the path through the ride height valves opens and the coach goes to the driving or ride height. After that the ride height valve closes and the coach should sit without dropping. So I think your problem with the rear settling down has nothing to do with the manifold. For both sides to drop at the same time you need simultaneous failures of the left and right rear solenoid valves as well as some means of creating an open path for air bag air to exhaust.

I cannot remember all the hoops you have jumped through on this issue, but I keep coming back to the point where to get this type of leak down the cause has to be something common to both sides and the only thing I can envision doing it is related to the tag lift and the 3 port valves between the drive and tag axles. Have you verified that if you lift the tag and get the drive axle air bag pressure as high as possible that the problem still exists, or does that make it go away?

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Joe testing new server.

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Jon, Good explanation on the valves.

No, I have not tried that, so you are saying to air up coach to ride height, then raise the tag, let the coach raise as high as it will, then turn the switch off and let it sit to see if it drops, correct?

And, when the switch is off, no valves on the manifold should be electrically activated, right?

Thanks for the picture Tom.

[Bob]

Exactly.

Please do this specifically. Make sure the HWH is not functioning. I don’t know the HWH system or how it relates to our leveling systems, but we do not want it working behind the scenes.

Start the coach.

Using the level low controls bring the bus up to the drive height as a starting point.

Lift the tag axle and leave it up from this point until the duration of the test

Using the level low controls manually raise the left and right rear to the maximum extent.You may have to have the compressor cycle on and off a few times at each side to insure you have all the air pressure you can get into the drive axle air bags. The tag axle air bags will be deflated.

Turn off the key. Measure the height at the rear, each side.

Here’s what we will learn. The three port valves on each side of the coach between the tag and drive axles should have closed the path between the drive axle air bags and the tag on each side. If they are both leak free the rear of the bus should not drop. After time the coach is going to settle or not. That is what we want to find out. What has been done is you have taken the cross connection between the left and right sides of the coach out and there is no way I can see possible for both sides to simultaneously drop.

Prior to lifting the tag axle both three port Norgrens were only opening the path for air between the drive and tag axles and the only way I can imagine at this point that the rear would drop is if they were both receiving some pressure from the tag lift pilot circuit and bleeding air out of each tag. or equally obscure is if they both had a leak of the same size. That is so remote a possibility I cannot see it being possible.

Hector……if you are out there have you any thoughts on this?

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testing

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Does your system have the extra R-14 to disable the tag brakes when they are lifted?. Do your tags auto lift when you turn your coach off? Does the Chev part of you screen name denote a hobby? Bob 69 blown/tubbed pro street corvette.

[Bob]

Bob.

I think the auto tag lift or air dump was no longer on coaches of Jerry’s vintage. But any time the tag is lifted, part of the system logic is to disable the tag axle brakes and I think that has been and continues to be on all coaches.

[Peter]

Testing mail connect for reply email.

[Jerry]

My 98 XLE does not. Didn’t know about H or converter mod to system. Almost seems like something back feeding from both sides of air bags in rear only two things in common are tag lift and air supply to bags. ck valves in leveling (manual) valves should take care of that. The R-14 that disables tag brakes also is tied in to tag lift norgren valve for signal. That about all that is in common that I can think of.

[Archived]

Bob, my tags do not auto lift. The Chevy in my handle was from me being a Chevrolet-Hummer dealer for 12 years. Drag racing is what I do for fun.

Jon, I just went out and aired the bus up to ride height, then raised the tag, when I do that, the bus will sag by 2 inches, and will not raise any higher than that. I cut it off with a 10″ measurement from the ground to bottom of bay. I’ll go back out late tonight, or in the morning to see if it sags more than that.

I have never been able to get the Prevost Level Low switches to do anything. When I try to raise it by them, it does nothing, and when I release the switch, it sounds like it releases air for a couple of seconds. So, to level, I always use the HWH. Don’t know if that is a clue to my problem or not.

[glen]

I think the fact the HWH is completely overiding you Prevost level low is a clear problem. To what extent it contributes however is beyond my level of understanding. I can choose the easy way out and say that might be the problem, but I would rather you try to get the coach up as you suggest and in some way disable the HWH, even if you have to go so far as to take the electrical connectors off the coils on the solenoid valve manifold or pop all 5 C clips and pull the 5 coils so we are assured nothing is sending any pneumatic commands to the suspension.

If you do that and we are confident the HWH cannot influence the suspension and the coach leans or sags down we can be assured you have a leak.

The fact the rear will not raise to ride height or above with the tag lifted is not a concern or a surprise. Depending on how much weight the tag axle carries, when you lift it you are asking 2 air bags per side to do what three per side have carried and it might just be too much weight for the two to raise with the available pressure.

If you decide to disable the HWH using the method I suggested above (clear overkill, but effective) why not start with the coach at drive height, and if it sags, put things together, then try lifting the tag and see if there is any change. Or for now leave it as long as you believe the HWH is not working.

[Peter]

Sounds like a plan Jon, I’ll leave it like I have it tonight, and tomorrow, if it has dropped, I’ll start with removing the wires/or solenoids as you suggested, and go from there.

Happy New Year !

p.s. I probably won’t be able to stand it, and I’ll have to go back out there tonight and “look” anyway LOL

[Jerry]

When you find it== will be like a light bulb coming on.. been there on that one.. I have rebuilt Mine on the 98 XLE from scratch.. Bob