Air Pressure Switch Problem

[Larry907]

I've got a warning message on my dash that says "low air susp" and a buzzer to go along with it when I release the brake and try to drive. A local RV service center identified the problem as a bad air pressure switch (Medallian part #104618), but said it will take 4-6 weeks to get from the manufacturer since the part has to be made. Does anyone know of a company that might have this part in stock? Thanks for the help!

[EngineerMike]

That's gotta be a simple pressure switch w/a buncha substitutes. I did a search at Ryder Fleet Products for air pressure switch and got several hits. You just need to determine if it is normally open or normally closed, and what pressure to activate (I'd guess 80). You could replace it w/the OEM version when they get around to "making" it, but a substitute part should do fine.

[APEXMAN]

I had that on my Apex and it was the HWH brain box.It was causing my lt rear air bag to dump the air so I crawled under the coach and unpluged the valve.Called HWH and they said if it happens again just unplug the canon plug on the box until I get another box.

[EngineerMike]

There is an 800 # for Medallion on this doc that may get the pressure switch sooner (or maybe you'll get the same story). Hope it helps.

[Larry907]

EM & APEXMAN...thanks a lot for your comments. I went back to the service center to see if they could just replace the pressure switch with another brand of switch and they said it's unfortunately not just a pressure switch. The problem is an electrical board that mounts behind the dash that also has a pressure switch built into it. They sent me a picture of it that I'll try to attach to this note. They tried to get a replacement part through a company that bought a bunch of WRV's parts, but this one wasn't available, so it has to be manufactured.

[Wayne R]

Larry907. That is the same switch I had go bad last summer. I replaced it with a mechanical air pressure gauge for $30.

[EngineerMike]

The "idiot light" modules are made by Actia. They can frequently repair a part on one of their assemblies if the part is replaceable, or else they'll make you a new gizmo. Their U.S. automotive office # is (574) 264 2373.

Or you could contact this guy and see if these are the same version you are using. He bought a buncha stuff from the WRV auction.

[Larry907]

Wayne - What did you do with the wiring that's connected to it and the warning buzzer?

[Wayne R]

The rest of the idiot light cluster still works properly so it remains plugged in. I was able to lock the pressure switch in the on position by using a small screw driver. I may have just got lucky. If that had not worked I would have probed the circuit board until I found what 2 terminals to short or open. I figired I did not have much to loose. My recolection is that idiot light cluster costs about $350.

[EngineerMike]

Here is a guess at the setup-
Pressure switch consists of a Normally Open set of contacts and one or two wires; if one wire then it is signal voltage and the metal switch body is ground; if two wires one is signal volts and other is ground. Pressure at an adequate level pushes the contacts together to make contact & "tell" the Actia setup that air suspension has adequate air.

If the wiring is available, you could intercept the air hose and wiring and install a new parallel pressure switch made for say 75 psi. This is way better IMO than getting a rebuilt or new solution from Actia, as you can then replace the switch yourself next time it fails and you don't need the proprietary system's sending unit.

You could also tee into the air line and add the pressure gauge. Or alternatively, you could install the pressure gauge & connect the wires for the Actia sender, but this makes you the warning system for checking air suspension. IIWM, I'd go parallel, cuz I like one thing about idiot lights & buzzers- I'm an idiot.

[EngineerMike]

Boy did I lie like a dog in the dirt w/fleas.
I pulled mine out and Actia certainly painted us into a corner on this. There is a single air hose going into the back of the light cluster/Annunciator via a push fitting. Zero accessible wires.
You either open up the circuitry and play w/the PC board parts, attempt a full bypass like Wayne did, or send it into Actia for repair. Sorry for the false hope.

Larry- you have two air inputs on the lower light cluster. I have only the outside one of the two connected w/an air hose, middle position nipple is there but no air hose connectied. First, what year coach do you have? Second, got any idea what the middle position air line goes to/comes from?

[Wayne R]

Unfortunately I believe the idiot light cluster has a logic board and intercepts the status of the air pressure switch and signals the Speedo cluster which displays a message and turns on a buzzer. When I unplugged my lower cluster the buzzer did not come on indicating to me that it is probably a normally closed switch.

[Larry907]

Mike - I've got a 2006 40' FDTS and no clue on the other air line.

[Wayne R]

Larry, Maybe it is supplying air to the park brake switch?