Air lock not functional ....

[Ray Davis]

So, on my previous XL2, the air lock automatically engaged when I released the parking brake (and possibly was in gear?). In my 93, I had to manually push a button for the airlock.

On my current XL2 the airlock does not engage. There is a door lock button, but it locks the regular deadbolt, not the airlock.

So, I need to start tracking this down. The question is where would you start looking? Any advice would be appreciated.

Thanks,
Ray

[Jon Wehrenberg]

I would initially be quick to say that is a Marathon question, and in part it may be, but on my coach thanks to my quest for finding a leak I find the door air lock is on the Prevost aux air system and not the converter's.

However, Liberty has integrated the control for the lock into their switch clusters. I think step one is to find where Marathon or Prevost has the switch. If it is automatic you need to find where it provides power to the solenoid valve, and if a Marathon controlled lock you need to find out how they deal with the power to the solenoid.

I want to make one very important point here. When we had the bus fire we were about 1/2 second away from not being able to get out of the coach because the fire had burned up the batteries. Apparently when the floor slide and air lock would not retract when I pushed the butttons (while rolling onto the shoulder to get stopped) the second time I hit the switches they did retract, just as the entire bus electrical system went dead.

If I had a coach with automatic engagement I would disassemble that feature or figure how to escape the coach with the door locked.

[Petervs]

First remove the cover panel in the door frame area that has the air cylinder behind it.

Then, see if you have 12 or 24 volts at the solenoid when you are trying to lock the door. If you do, the solenoid is probably bad. Check the ground wire too of course. If you do not, bring some power to it to prove that it functions when voltage is applied.

Then, figure out what the source of the voltage should be.

On my 94 Marathon, the power comes from either the switch by the door, the switch on the dash, or the alarm system if the key fob is used.

As soon as all power is removed from the solenoid, the lock opens. So in event of a power failure, totally dead batteries, whatever, the door would fail unlocked.

[Ray Davis]

Thanks Peter, I'll give that a try? So, the solenoid should be right in the vacinity of the air lock itself?

I was looking at Prevost wiring and pneumatic diagrams last night on the Prevost site, and it doesn't specifically say where anything physically is located, but it appeared like there was fairly long air lines to the door latch?

I've also got a note into Marathon tech support. We'll see what they say, but certainly removing the panel right there is the first step.

Thanks,
Ray

[Petervs]

The solenoid is right next to the cylinder.

[gmcbuffalo]

Have you check the circuit breakers in the drivers side electical panel? That could also tell you if it is 12 or 24v.

The last time I saw a gutted bus before conversion there was a air clyinder in the wall next to the passengers chair.

GregM

[Ray Davis]

I'm going to look the next time I get out to the bus. The airlock on an XL2 is located above the door, in the top right corner, unlike on the XL models. I assume there is a circuit breaker for it, and I've been trying to find a reference which would indicate which one.

Ray

[jack14r]

On my coach I had a problem with the air lock,the solenoid is to the right of the door(behind a lighted grab handle) the air cylinder is behind the door panel,there is a 24 volt relay and circuit breaker in the steering bay for that circuit.I had a open diode on the solenoid that would open the circuit breaker when I released the brakes,this breaker also supplied 24 volts to the air solenoid for the air to the rear of the coach(belt tensioners) and also to the waste gate on the Detroit Diesel,this little diode created havoc until I pulled the relay for the air lock and then everything else on that circuit worked.

[Ray Davis]

Jack, thanks for the info. Do you happen to remember the CB number?

[jack14r]

Ray,The circuit breaker is #27,the relay is # 108.I would check both.

[Ray Davis]

Excellent. Thanks Jack.

[Ray Davis]

So, a little followup to the air-lock issue. As it turns out, I spoke with Kevin Erion as we got ready for our trip out to ORA Rancho, and his air-lock was in-op as well. I hear that Jdub's may also not work.

Well, Kevin spent a good part of a day tracking things down, and I spent the good part of an evening pooring over schematics from Prevost. It turns out tha there are two switches in series with the airlock, which are designed to prevent it from activating, or to de-activate it. One switch is the door-closed switch, and the second is a micro-switch attached to the door handle itself.

Earlier this week Kevin tracked his problem down to the fact that the switch attached to the door handle was out of adjustment. Once that was re-adjusted, his airlock was functional.

Today, I brought my coach over to Kevin's shop. After a bit of checking, we took the door apart, and found that my switch there was just fine.

Ultimately we found that the door-closed switch, which is behind the door arm in the front dash area there was a missing wire. Yep, the wire that went to the next switch down the line (the handle). It wasn't only missing, it was wire-tied in such a way that it could never reach the switch.

A short time later, we had the airlock operating on my coach! Given that Jdub's coach is closer in age to Kevin's, I'm gonna bet that his problem is the microswitch adjustment as well. They changed the mechanism on my coach.

Kevin, thanks for all the help today! I would have taken me hours longer to track it down!

Ray

[Kevin Erion]

Ray, Thanks, fun stuff! I did get a call from Jdub and as it turned out, his is working fine. Must have confused it with the muffler bearing not working!