2004 Monaco Executive Tag Axle

[paulusmagnus]

Help needed to locate the Mac Tag solenoid switch.
I own a 2004 Monaco Executive 43 PBQ with a tag axle, Cummins 500 ISM and the HWH automatic air leveling system. When I lift the tag axle the system continues to lose air lowering the rear of the coach. I believe the exhaust function of the solenoid valve is sticking open and causing the problem. My big problem is I cannot locate the specified MAC 225B-601BA solenoid switch on the coach by visually inspecting the engine compartment. Based on some posts on the FMCA forum I was lead to believe it would be next to the Tag axle pressure regulator or near the air intake manifold on similar Monacos. It is not present at either location. The official Monaco air lines schematic for the tag axle show the MAC solenoid switch but not its location.
Before I start crawling under the coach and tracing air lines and electrical wires I hope that someone out there can inform me of where it is located. This forum has always been a tremendous resource for me in the past. Thanks.

[DtBt]

The tag lift is supposed to exhaust air from the air bags via the HWH solenoids for the tag axle. The solenoid to lift the tag air cans is probably located on frame rail on passenger side of the engine. At least that is where my friend's 02 sig is locacted. My 05 Panther has the solenoid next to the tag pressure regulator in engine compartment.

[paulusmagnus]

Would it be in the engine compartment or further forward near the Tag Axle? Anyway thanks for the tip. I will check over the weekend.
PaulusMagnus

[DtBt]

It is normal to loose some air and the coach to slightly squat when the tag is raised. The MAC solenoid you cannot locate is used to supply air to the lift canisters. Take a look at the HWH Air leveling service manual. Your problem may lie in that system.
http://www.rvtechlibrary.com/chassis/HWH2000_owners.pdf
http://www.hwhcorp.com/ml31043.pdf

Page 11 0f 26 of service manual has the troubleshooting for the tag lift. I'm pretty sure wire 3800 is used since the external MAC valve is used by Monaco ( see schematic). The control box is located in main (large) basement compartment over a small removable panel in ceiling covering.

Here is my air leveling schematic. Yours should be similar.
https://www.mediafire.com/?lm23o1weg1nwoby

My friends 02 sig did not have air leveling but had a row of air solenoids including tag lift on upper frame rail passenger side accessed from closet floor hatch. They had wiring and air lines covering them and were hard to see much less work on. Trace the line from the lift canister to locate the MAC valve.

[paulusmagnus]

DtBt
I finally had a chance to crawl under the motorhome. Following your advice I traced the green and orange lines back to the rear of the motorhome to the tag axle solenoid which was located next to the Pressure regulator. What caused an enormous waste of time and effort was Monaco had spray painted all of the lines, including the yellow and black airlines to the Regulator BLACK starting from the transmission back. That is a guaranteed way to defeat the idea of color coding identification. In addition, the solenoid is definitely not the Mac solenoid specified or in the schematics. I was unable to identify the rather unusual cylinder solenoid Monaco used because it too was sprayed painted black.
I confirmed that there is good 12v present at the solenoid.
My question is do you have the Mac 225B-601BA solenoid on you coach? If so to which of the three ports are the green and orange lines connected? I plan to call the MAC distributor in Phoenix from whom I bought the solenoid for additional information. Anything you can provide would be greatly appreciated.

[DtBt]

I'm sure my solenoid is like yours. I do want to emphasize that this solenoid supplies air to the lift canisters. The dump valves (called tag enable by HWH) for the tag air bags are on the HWH tag six pack along with the tag raise and tag lower solenoids located under coach over the differential.

[paulusmagnus]

I finally had an opportunity to go through the entire HWH system and verified it is operating properly. I did find the FRP Bd#3 ( Intellitec 73-00830-001) to be defective and replaced it with the same Intellitec Board Monaco PN: S16619560 it is called a FRP Logic Board. Cost about $175. I also replaced the Tag Lift solenoid valve with a new MAC valve. There is air to and thru the MAC valve to the orange air line for the Tag lift. However I see no movement in the Tag canisters on either wheel.
I know there is a T in the orange line. Is there another in line valve that would cut off air to the canisters? If the canisters are both bad(which seems a little improbable) where can I get new ones or if they can be repaired a repair kit? I cannot crawl under the coach safely to try to find the manufacturer or the Part No. for the canisters without a lot of work and no proper place to do it.
Any help you might have would be deeply appreciated. Otherwise I might just have to take it in to a qualified service facility. Hoping to know the manufacturer and Part No I could eliminate delays caused by having to locate and ordering the part.
Must say one thing I have learned a lot of valuable information from everyone contributing.

[DtBt]

I have read in this forum from Mike Canter I think that if one levels with the tag up and engine running it can blow the canisters. The air bags are working against the canisters. This is a design error in the HWH leveling logic. Upon his recommendation I added pressure relief valves to my canisters. I'll try to find the reference.
It should be easy to check the canisters. Air should be gushing out of the area around the the actuator.

[Topman]

If the diaphragms are blown, it is a cheap and easy fix.
You should however be able to hear if they are leaking when activated.
Iver.

[paulusmagnus]

Hi Guys,
Thanks for the two helpful posts. I always learn a lot when I get on this forum. It appeared to me that the canisters could be repaired if the diaphragms were damaged. I was hoping to find a reference to a kit repair number, such as from NAPA or the manufacturer. I would be very interested in the reference to the pressure relief valve solution.
I plan to take the coach in Monday to a facility where they service a lot of trucks, farm equipment etc in Coolidge, AZ. I am sure I will find out a lot then. Your help is greatly appreciated.

[paulusmagnus]

Just an update. Took the motorhome in for service on the Tag axle lift issue. One lift canister had a blown diaphragm and the other was leaking. Replaced both with new canisters(they are also called air chambers) NAPA PN: MBI SC 30. Cost$41.99 each. I found that the repair diaphragms (as well as the canisters) are readily available from many sources. Having a service technician repair them is about a wash with buying them new. I was also surprised when the technician told me if I decide to repair the old canisters to use extreme caution as they are under heavy spring tension and could cause injury if not carefully taken apart. He said that they always take them apart behind a clear plastic head to waist shield. Anyway the learning continues and I again want to thank you for all your help.

[Topman]

I'm sure the technician would be referring to "spring brakes" or "maxi-brakes"
when he said to use caution when servicing. Proper caging is essential.
The air cans used for lift (at least in my coach) have just a simple spring system which pushes the diaphragm back when the air is released.
I replaced mine without any problem.
Iver.

[paulusmagnus]

Thanks for the reply. The air canisters on my coach are like yours Iam sure. It is a single chamber unit. When I went online and researched the device it looked like it had a very small spring thus I was somewhat surprised when the technician said it should be taken apart with caution. Anyway I learned a lot.
When I got the coach back the tag axle lifted just enough to clear the surface and the wheels could be hand rotated. I think I would like to adjust the chains to lift them a little higher. To do that I thought about backing the tag on some 2x12 boards, thereby loosening the lift chain and then shortening the chains by one link. Is this a good procedure or is there a simple way? I like learning from persons more experienced than I am. Thanks for your help.
Paul

[DtBt]

To ensure the canisters are protected from inadvertent lift with air leveling activated install 150# safety valves 3/8" MNPT. There is a allen head plug you can remove to install from the exterior of the wheel well. I got mine from ebay.
Looks like this http://www.amazon.com/Control-Device...8+safety+valve