1993 wb40 – hwh leveling sys. Question

[RSeibert]

After going through this a couple of times, it seems there is some sort of air pressure signal the HWH system wants to see before it will work …

Twice now I’ve tried to activate the HWH system and either let it down or level it out – All I get are some distant solenoid “clicks” and the motor doesn’t react.

First time was this spring when I tried to retract the jacks, so I just threw up my hands and went on to other things – Specifically airing up at the rear Schrader for the purpose of adding MMO to the system.

Shortly after I tried the HWH and … It “fixed itself” (as this bus seems to like doing on occasion). So I wondered if it was related to the air system.

Fast forward to today – I wanted to get it up on the jacks and level it out – Nothing … Then remembered what happened in the spring, so I aired it up and same thing, HWH started working again!

Anyone know if this is correct and / or exact nature of the interface between air and HWH systems?

[mose]

If like my '91, I don't think there's anything involving system air for the HWH. There's two big relays near the pump motor. One relay is a master relay that provides power to the valves, the other relay runs the pump. Then there are 3 Short-Stop circuit breakers that provide power to the various control valve solenoids. I had two separate issues with the connections at those circuit breakers that caused certain portions of the system to not function. Once I replaced the breakers and cleaned up the connections, all was well.

The relays and solenoids are all located above/behind the entry step. It can be difficult to get in there, but the diagnosis is quite simple.

EDIT: Suppose I should add that it can be a dangerous job and to be sure to block up the frame and watch out for the air step and jacks.

[RSeibert]

Hi Mose.

Thanks for the reply …

Pretty sure the ’91 and ’93 are really similar if not identical for the HWH system …

But I found info. in the Main manual for the bus referring to the HWH – Pages 15-1 through 15-3 specifically (See attached clips from these pages).

Most specifically from page 15-3:

“If the park brake is not set when the “I” button is pressed, the “NOT IN PARK” light will come on and the system will not operate”.

I did not notice the "NOT IN PARK" warning come on before I aired up ... And, I do know the park brake was set. But maybe there needs to be air pressure to send a "Park" signal to the HWH ???

But, like I say, twice now, my jacks seem to work well, but only after getting air in the system – Does your manual say the same sort of things?

[mose]

Ah. That is different/upgraded from mine. I don't have a 'park' input (and thus have the ability to lower the jacks and make sparks while driving).

I would GUESS that the park input would be tied to an air pressure switch on the parking brake air circuit; similar to the high idle, which won't engage unless in park.

So does the 'not in park' indicator always correlate to when it works or doesn't work?

A wiring diagram for the '93 may help to figure this out.

[BrianS]

Mine has an LP-3 low air pressure sensor up in the front left bay connected to the HWH system. If disconnected, my jacks will not work.

[RSeibert]

Hey guys.

Thanks for the replies ...

This thread answers a bit more:

https://www.wanderlodgeownersgroup.c...ad.php?t=26542 - Exactly how mine was responding:

Originally Posted by pvlmal

transmission is in neutral and parking brake on and showing on -on the hwh control panel.(light)
when I push the on button it lights up and then push again and it begins to blink, but no had sound or action from the unit.

Randy's telling response to this:

Originally Posted by Randy Dupree

I had this happen twice in a week,i had to release and reset the parking brake with a full tank of air,fixed it twice.

I've been scanning the schematics + looking for the wiring for the LP-3 low air pressure sensor Brian mentioned above - Not found yet, I'll keep trying!

Thanks,

[Randy Dupree]

Funny,it never happened again.
I guess the switch was sticky?