Main > Pneumatic > Level Low Problem

old post - new post - new reply - closed threa

  1/14/2012 8:44:31 PM - Thread - DKO  
Level Low Problem

A couple of days after viewing Hector's great lesson on Prevost Suspension Systems I have developed a problem with my Level Low. I can raise and lower each side in the back and I can raise the front but I can not lower the front. When I push the button it does nothing. My wife usually levels while I am setting up outside and she said that lately she sometimes had to push the down button a couple of times or hold it down a few seconds before it would kick in but now it does nothing.

My controls look like the ones in Hectors demonstration. Here is a picture of mine.

It seems to me that the down button is fine since it works for left and right.

Two questions...

1. Any idea what the problem is and how it can be corrected?

2. Any way to release the air by any other means until I can get it fixed?

Internet service is going to be sporadic for me this week so you will know why I may not respond immediately...

Thanks in advance...

DKO



Home is where you go when there's no place else to go!
1995-96 Prevost XL Vantare
Detroit 60 Series
Toad-2006 Scion Xb
1997 Featherlite 24' Trailer
www.boggsblogs.com
 
  1/15/2012 6:44:25 AM Jon  

DKO

One of the issues with our suspension systems is their differences. Hector's program shows the basic operating principles, but his system operating logic will vary from mine because Prevost made a change between when our two coaches were built. Having said that I find the only way I can trouble shoot any Prevost is to find out what is not happening when I command something to happen. Remember that not only are our systems potentially different because of minor changes in design by Prevost, our converters also modify how the system works. For example you may have an HWH over ride on yours that could come into play. My Liberty has the addition of 2 Norgren valves to work within the Liberty designed leveling features.

Back to determining what is working and what is not........I start with my voltmeter to determine when I give a command at the dash (raise, lower, etc) and I verify the solenoid valve on the five valve (sometimes four valve) stack is getting an electrical command. In your case of lowering the front I would check for power at the second solenoid valve down. If it is there I then verify the valve is functioning. From there I go to the Norgren valve that receives that air signal. etc. In other words I start from the beginning and work my way down the system, verifying I have either voltage or air where I am supposed to have voltage or air. 

In your case you might wish to bypass the step by step checking to find out what component is not common to the rear systems and raising and lowering them. That is another place to start. I cannot answer your question specifically because I know my Liberty, but I do not know how your converter or Prevost set up your coach. That is why I need to always start with the basics.

To make your front go down, at least to driving height just put the control in the driving or road position. Again, every converter labels the switch positions differently, so while mine says "road" yours may say "drive" and I have seen one in which the driving position for the switch was labeled "automatic".



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  1/15/2012 7:11:32 AM TexasDrifters  

If the suspension system will raise and lower the left and right rear, but not the front, my first guess is electrical.  The left and right rear suspension uses the same solenoid, the exhaust solenoid mounted in the level low mount, under the passenger seat as the front does for adding air and venting.  If you can successfully add and vent air from both rear, but not the front, then electrically things are not working.  I have noticed that the rotary switch will need to be spun around a few times when sitting a time with no use.  Also, I have removed and cleaned the raise/lower switch on mine.  You should hear the solenoid energizing from the drivers seat when working the raise/lower button on all three positions. 

Select the rear and push raise/lower button.  When you select front, you should hear that same sound.

 

My suspension presentation addressed the Prevost system only.  On my Country Coach, the leveling system uses the same solenoids as the Prevost system for leveling.

 

My suspension presentation addressed the Prevost system only.  On my Country Coach, the leveling system uses the same solenoids as the Prevost system for leveling.

Let me know what you find.

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/15/2012 7:47:56 AM Truk4u  

If it's the 5 Norgren Valve assembly under the driver seat in the steering bay, the coil and valve will look like this when taken off:



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  1/15/2012 9:46:50 AM TexasDrifters  

No, it is not one of the five pilot solenoids mounted on the rail.  The particular solenoid is mounted on the level low system plate located in the pneumatic bay, below the drivers seat.  It is the bottom solenoid.  However, he stated that both rear systems work correctly.

It seems the exhaust/control solenoid is not getting voltage when the control selector is pointed to front.

 

Hector

 



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/15/2012 10:40:06 AM robertglines1  
Clean & grease

Electric contact cleaner and then diaelectric grease when reassembling.  Both at switch and connection at coil..  ??? a start for corroded connections.



98 XLE home built triple slide-SW Indiana
 
  1/15/2012 1:50:06 PM TexasDrifters  

Good advise concerning cleaning and dielectric grease.  The rotary switch on mine is "complex", meaning if you take it apart, be very careful to realign the switch timing correctly on the switch. 

I was having intermittent issues with mine not raising each time I pushed the up/down rocker switch.  I would need to do this several times and hold my finger on a certain position on the switch(and sometimes hold my breath).  I solved the issue my removing the up/down rocker switch, disassembled, cleaned, lubed and reassembled.  Now is works very good and repeats the function exactly.

The rocker switch is not as complicated as the rotary switch.

Good Luck.

 

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/15/2012 7:07:29 PM Depewtee  
Vintage Liberty Leveling System

Here are some pictures of my "vintage" Liberty leveling system.


I am still not completely sure when I should keep the toggle switch in "off" and "on."  The valves work and level the coach just fine every time!

Brian



Brian and Cathy
1981 Liberty Le Mirage
Florida Panhandle
 
  1/15/2012 7:19:03 PM Jon  

Brian, The only thing that is critical that you need to know is that you have your switch(es) set so the ride height valves are functioning when you go down the highway. You cannot manually set your height and expect it to stay there once you start driving.

To determine if the ride height valves are in the circuit (and not bypassed as when leveling in a campground) lower the coach all the way and then set the switch to what should be the position for driving. Step outside and if the coach goes to the driving height that is the switch position to use when driving.



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  1/15/2012 7:21:27 PM Truk4u  

Hector,

Why couldn't it be the valve portion of the valve/coil assembly? It seems possible the valve could work for the air up, but not for the down (exhaust). Simple solution would be to just swap out one of the other coil/valve assemblies to rule that out.



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  1/15/2012 7:29:18 PM Depewtee  

@Jon - I will play around with it and once I figure it out I believe I will relabel the on/off switch to drive/park.

Brian



Brian and Cathy
1981 Liberty Le Mirage
Florida Panhandle
 
  1/16/2012 8:11:57 AM TexasDrifters  

Brian,

Thanks for sharing the photos.  Yours is the first system I have seen with this configuration.  The leveling systems I have seen, incorporate a rotary switch and a up/down switch. 

I believe Jon owned a Liberty in this year range.  Your photos probably bring back memories for him.

Again, thanks for the photos.

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/16/2012 9:52:12 AM Jon  

My Liberty was a 1987 and despite it being more than 20 years old the leveling system controls are exactly like my current ones. The system itself is a little different than today's.




Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  1/16/2012 4:04:51 PM DKO  

Thanks for your thoughts guys. As I suspected internet service is going to be hard to come by this week. I can access this site from my iphone but have not determined how to post or reply here from my phone.

Today is a very nice day here although the wind is about 25mph. The next few days look positively frigid so I want to make progress if I can.

Here are a couple of pictures of my set up. The picture of the controls is in the original post.


I would not have known this was related to the Level Low if it had not been for Hector's demonstration.

I double checked and when the selector is on left or right and the down button is pushed the air is released and I can hear the solennoid engaged. When the selector is on front and the down button is pushed there is nothing at all. No air, no solenoid, nothing. A bad solendoid seems likely to me.

Where do I need to check for voltage? As you can see, the wiring is covered with some sort of goop. Do I check under that?

As I said, I may not respnd right away but I can read your responses....

Thanks,

DKO



Home is where you go when there's no place else to go!
1995-96 Prevost XL Vantare
Detroit 60 Series
Toad-2006 Scion Xb
1997 Featherlite 24' Trailer
www.boggsblogs.com
 
  1/16/2012 4:52:42 PM Jon  

Before you zero in on the solenoid, check for power at the top and second solenoid coils when you command the front up or down. I'm going by memory and I think both should be energized when you ask for the coach to move up, the second one down when you ask it to go down. Hector.........if my recollection is wrong, spank me. My point DKO is I don't think you are getting power through the rotary switch with the selector knob in the front down circuit.

I cannot recall if Hector's program shows specifically which solenoids are activated for each specific function, but regardless, to trouble shoot you first must verify the solenoid coil is getting power. If it gets power and no action ensues then check the coil, and only then start looking at the pneumatics. Every single switch position on your controls is going to result in one or more solenoid coils getting power. This presumes the key is "on".



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  1/16/2012 8:13:37 PM TexasDrifters  

I give this a try.


To recap, you stated that you could raise and lower, the left rear and right rear, however, you could only lower the front.  With these symptoms, my input is as follows:


For example, when you raise the left or right rear, the "tan/lower" Norgren in the picture is energized, aligning aux air supply to the five port Norgren that control each air bag set.  So if your right and left rear is able to raise, that verifies that the Norgren is indeed being activated.  The Norgren (tan/lower) is activated by a small pneumatic cylinder on the side of the valve assembly.  One of the small (black) pilot valves mounted on the supply rail supplies air to the small pneumatic cylinder, thus moving the valve spool, re aligning air ports.  The reason for this detail is to let you know that with the symptoms presented, the control/exhaust (tan/lower) solenoid is functioning. 

As far as checking voltage, this can be more of a variable.  My pilot solenoid coils are all 24 volt, some are mixed with 12 volt coils installed by converters.  You will need to sort this out to determine what the correct voltage should be.  I do not remember which pilot solenoid activates the control/exhaust Norgren, however, trace the 1/4 inch tubing from the small pneumatic cylinder, mounted on the side of the (tan/lower) solenoid to the pilot valve mounted on the rail.  Check voltage on the wires feeding this coil.  It should be "hot" when you select right/raise or left/raise rear.  Then select front, push the raise button, you should read the same voltage as when you pushed the raise button with the left or right rear selected.  (Whew!) 

Do not overlook the possibility of having dirty or corroded contacts in the rotary or especially the raise/lower switch.
I would never attempt to work on any suspension control system without a pneumatic and electrical drawing in hand for the particular coach. 

These systems are complicated and I have not found any quick or easy way of troubleshooting.  Also, never crawl under a coach without having it properly supported with jack stands.


Good Luck.

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/17/2012 2:11:54 PM gmcbuffalo  

That rotory switch can get real dusty and dirty, spray the contacts generously with electrical contact cleaners.  



Greg & Huong Meiling
92 Beaver Conversion # 25
05 Excursions toad
 
  1/18/2012 12:50:58 AM gmcbuffalo  

I don't think it is a switch, either the up/down or rotory.  But somewhere between the "down" side of the up/down switch and the suppy valve solenoid you have a break.  Connectors C180 or C181.  C180 is the connector to the diodes, C181 is the connector to the five solenoids  At the top of the drivers electrical bay you should see a series of diodes.  They should be the only compoenet between the switch and solenoid.

   Does one of the diodes looks bad?  

   Is the connector to this panel of diodes attached good?  

   Can you wiggle or clean the connector to it and make sure you have a good contact?

The rotory switch gets the 24volts and determines by it's position what airbags system to pass the 24v thru the up/down switch.  This u/d switch pass 24v to the supply valve solenboid if it is in the down position, exhausting the bags, it pass the 24v to the front solenoid valve if it is the up position to inflate the air bags. then the voltage goes to ground.





Greg & Huong Meiling
92 Beaver Conversion # 25
05 Excursions toad
 
  1/18/2012 7:05:50 AM Jon  

While Greg's post has merit, one thing all need to understand is the leveling systems on our coaches have many variations due to Prevost always improving the system, but also in addition our converters also may have modified the systems to add features. What may be true for my Liberty chassis is not true for Hector's CC, or Greg's Beaver.

But the diagnosis process will be the same and that is to start at the beginning to insure the electrical command given at the buttons and dials next to the driver are in fact getting to the solenoid valves on the manifold. Once that has been determined, then the diagnosis follows the air path, starting with insuring the solenoid valves are opening, the pneumatic signal is getting to the Norgren spool valve, and that the spool valve is shifting internally sending or dumping air as commanded.

It sounds complex, but it is not, it just requires an understanding of what happens when a buttonis pushed and then verifying everything along the path happens as designed.

What is important however is to understand the basic system operating logic for your coach, and then to determine if the converter modified it, and if so, how do those modifications affect the system operation. By the way, nobody can shoot from the hip diagnosing problems It is almost mandatory the trouble shooter has access to the pneumatic and electrical diagrams so if there is an issue it can be more easily isolated.



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  1/19/2012 6:18:25 AM TexasDrifters  

DKO,

What is the status of this problem?  Did you repair it?

 I am a curious soul my nature.

 

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/20/2012 1:09:00 AM DKO  
Thanks for Asking

Thanks for asking, Hector. It has been bitter cold and windy here so I haven't even tried to make heads or tails of it yet. We had some sunshine today but I was working on another project. I am sure I will have questions after I look it all over so please stay tuned....

Thanks again,

DKO



Home is where you go when there's no place else to go!
1995-96 Prevost XL Vantare
Detroit 60 Series
Toad-2006 Scion Xb
1997 Featherlite 24' Trailer
www.boggsblogs.com
 
  1/24/2012 1:03:46 AM DKO  

I spent some time trying to implement some of your ideas today. I definately have action in the solenoid for every function except for front DOWN. The solenoids do nothing at all then. 

The first two solenoids activate the pilot air (I think this is the term Hector used) on the two norgren valves. One for the tan norgren below and the other for the black norgren above. 

The bottom two solenoids operate when pushing the up and down buttons when the selector is on left or right and I believe as well on front.

The middle solenoid does not activate at all that I can tell. I tried taking some of the sealent out but I still could not get the leads from my tester to make any contact. Should I remove all of the sealant? Does the solenoid  come apart so I can put the meter on the wires? How does it come apart?

Is there a way to manually release the front air so I can lower the front end until I can fix this?

Thanks guys. I am trying to learn so thank you for your patience. Also still not much dependable internet this week so responses are slow from me...

DKO

Original picture

Picture today after I had removed some of the sealant just so you know what I am talking about...



Home is where you go when there's no place else to go!
1995-96 Prevost XL Vantare
Detroit 60 Series
Toad-2006 Scion Xb
1997 Featherlite 24' Trailer
www.boggsblogs.com
 
  1/24/2012 6:29:41 AM Jon  

DKO,

The center solenoid valve is the valve that is open any time the ignition is on and the selectors are in the position for driving. Those two conditions have to be satisfied for that valve to work. That is the valve that causes air to be routed through the ride height valves. Even if none of the other solenoid valves are functioning and the front end is as high up as possible, when you put the selector switch in the driving position and turn on the key the coach front end should drop to the height for driving. Is that what you are asking, or do you want to lower the coach all the way down in the front?



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
  1/24/2012 6:54:45 AM TexasDrifters  

 

DKO,

http://prevostparts.volvo.com/technicalpublications/pdf/pa1082-16.pdf

The above link is to Prevostcar.com website were you can find info on your suspension system.  It contains information concerning the suspension system and particularly, the level low system.  In section 16, subsection 12, their is a brief discussion of the level low and a pictorial diagram. In the diagram, the five pilot solenoid are labeled.

http://prevostparts.volvo.com/technicalpublications/pdf/d140196g.pdf

The above link is to a pneumatic diagram.  The particular diagram is for my coach, but it should very close to yours.

I can not encourage you enough to spend time using the Prevostcar resource for information.

The center pilot you have referred to is the pilot for road height.  When you select this position, all three of the 5 port Norgrens, two on the rear bulkhead in front of the differential and the upper solenoid mounted on the level low panel in the front pneumatic cabinet, align the air bags to your road height valves.  This process allows the coach to adjust to the road height valves setting. 

You should go to the Prevostcar website and look under publications to download you particular coaches technical manual for suspensions, a pneumatic diagram and an electrical diagram.  These tools will give you information for adequate troubleshooting.  This would be a very complicated task to resolve with this information.

Concerning letting the air out of the front.  That could be tricky and dangerous to disconnect the air tubing providing air to the front air bags.  Once this tube is removed, the coach will drop uncontrollably in the front.  This can be done, but please exercise caution.

From what you have told me in these post, I still am pointing towards an electrical issue.

I have sent you a private email with my contact information.  If you would like, contact me and I would be glad to chat.

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/24/2012 7:35:22 AM Truk4u  

DKO,

You have to determine which coil/valve is the front, I don't remember. Use a tester that can pierce the wire so you can confirm you have juice to both up and down function. If you have juice, swap out one of the other valves with the front and then verify it functions properly. To swap out, remove the c-clip and the coil slides off the valve. The valve is held to the body of the Norgren with two very tiny screws. Remove the two tiny screws being careful not to lose the tiny o-ring when the valve comes loose. The o-ring is on the backside of the valve. Swap out one of the other adjacent assemblies to verify the front functions properly. Like Jon pointed out, the center assembly is the ride height and only has juice if the key is on.

So, if you have no juice to the assembly, you'll have to solve that issue first. If there is juice at the coil, you probably have a bad valve. You could also have a bad coil even if you have juice, so the swap out will determine that. These assemblies are a common problem, I've had to change them out on every bus I've owned and carry a spare.

You don't have to remove any wires to do the swap. You will have to use that assemblies button function to operate the valve. In other words, if you swap out the right rear assembly, you will have to use the right rear raise/lower buttons to operate the front.

Refer to the picture I posted for you of the valve and coil separated.

 



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  1/24/2012 4:27:46 PM gmcbuffalo  

DKO

Is this your coach?

http://prevostparts.volvo.com/technicalpublications/pdf/D060815p19.pdf



Greg & Huong Meiling
92 Beaver Conversion # 25
05 Excursions toad
 
  1/25/2012 4:43:01 AM TexasDrifters  

Greg,

This is a great drawing showing the level low wiring.  It clarified much for me.

 

Thanks,

Hector



Hector Duplichen1995 Country Coach, XLV, S-60Livingston, Texas
 
  1/25/2012 11:39:01 AM gmcbuffalo  

DKO I think like Hector that you have a electrical problem.  If you can raise the coach above ride height and then put the switch in Drive and it lowers to drive height you don't have pneumatic problem.  The exhaust valve works.

That up/down switch is like a triple pole Momentary On, Off, Momontary On switch it should have nine wire attached to it.  You can see it if you look up from the Electrical Bay under the driver.  The center wires are probably the power wires from the Rotary switch, one for the Front, Right Rear and Left Rear.  With the Rotary switch in Front position have someone push down on the switch check the end terminals for voltage.  If you do this for one of the positions that is working you will know what side of the switch should have power when the down switch is pushed.  If this works go to the diode connecter and see if there is voltage then move to the solenoid and check.  I think that somewhere in this path you have a bad or dirty switch or a break in the circuit.



Greg & Huong Meiling
92 Beaver Conversion # 25
05 Excursions toad
 
  1/31/2012 2:24:14 PM DKO  
Thanks

Thanks guys for all the information, advice, suggestions and help. Thanks for the private message, Hector, and the contact information. I apologize for the lack of comunication last week. It could not be helped. I couldn't even get a phone call out most of the time.

I checked the connections that Greg mentioned. His numbers corresponded with the numbers on my connections. Everything looked good. No broken wires that I could see and all was clean.

Now it gets interesting....

I moved about 3 hours Saturday and when I parked I tried moving the front down just for grins and it went down like normal! I moved early Sunday morning to may location for the week and tried it again and sure enough it went down again.

Could it be that there was a problem with the connections that was resolved at least partially by messing with them?

Thanks again,

DKO



Home is where you go when there's no place else to go!
1995-96 Prevost XL Vantare
Detroit 60 Series
Toad-2006 Scion Xb
1997 Featherlite 24' Trailer
www.boggsblogs.com
 
  1/31/2012 3:32:55 PM Truk4u  

Probably some junk in the valve that passed.



Tom & Nancy
02 Marathon H, 732
08 Jeep Wrangler
 
  1/31/2012 6:07:17 PM Jon  

It is incredibly hard to diagnose problems on a forum because those of us offering advice lack knowledge of the coach and its history, we lack all of the senses we use when we are at a coach such as our eyes, ears and nose, and the worst part is while it appears we can communicate we really only scratch the surface.

So assuming all is well we can all feel good knowing somewhere in our answers may actually have been the key to fixing the problem. Using this as a guide I think now all members can see that on this forum we always give answers to questions, and on rare occasion we may also provide a correct answer.

If I had to guess as to the correct answer I would say using or wiggling the electrical controls was likely what has restored the operation of the level low.



Jon and Di 2006 Liberty Elegant Lady 2005 H2 Hummer
Knoxville, TN

 
   
© 2011 Prevost Community
Top of Page