> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto
wner-gmcmotorhome]On Behalf Of Walter M. Drew
> Sent: Wednesday, February 03, 1999 11:17 AM
> To: gmcmotorhome
> Subject: Re: GMC: electro level
>
>
> I have Electro Level II in 78 Royale. Everything works fine until I put
> it in auto and it leaks down to zero in under two minutes. Driver's
> side about 40% faster than passenger side. Walter
>
Walter, please excuse the length of this reply, but I think I can offer some
suggestions.
I recently went through my system trying to correct a leak-down problem in
general, and a malfunctioning level control on one side. In the process, I
learned a lot about the operation of the Electro-Level II system.
Fortunately, the system is quite simple. There are two compressors with
built-in exhaust valves. One for each bellows. Each compressor/exhaust
valve is isolated from its bellows with a solenoid valve that is actuated by
the ignition switch. This "locks" the pressure in the bellows when the
coach is parked. Each compressor/exhaust valve is controlled by the manual
switches when the system is set to "Hold", and by the level sensors attached
to the rear suspension arms when the system is in "Auto".
If you are having leak-down only in the "Auto" setting, then the problem
should be with the level sensors system. I would suggest that you check the
following:
1. Verify that the sensor arms are properly attached to the rear suspension
control arms.
2. If connected, are the adjusting screws tight and adjusted properly?
3. If everything "looks" OK, disconnect one side, and verify that the sensor
arm rotates freely. I had a problem with one of mine, but I was able to
correct it and save the $300+ cost of replacing it as the manual suggests.
4. If the lever rotates freely, see if your compressor/exhaust solenoid
respond to your manipulation of the arm. Note that there is a 14 - 28
second time delay built into the circuitry of the level sensor. If the
system responds, you should be able to fix the problem by correcting and/or
adjusting whatever was amiss.
5. If the system does not respond correctly, then I would suspect a faulty
sensor (hard to believe that both would malfunction in the same way) or an
electrical problem. If you try to track down an electrical problem, be
aware that the sensor provides a "ground" circuit for the
compressor/solenoid solenoids, and a short in the control circuit could be
to blame. The GMC Maintenance Manual X-7725 has the wiring diagram for the
EL II system.
Incidentally, the solenoid valve between the bellows and the compressor on
my coach was installed backwards. This was suggested to me by Bob at
Gateway. The GMC Manual specifically calls for the "arrow" on the valve to
be pointed to the bellows. I checked with the manufacturer of the valve and
verified that Bob is correct. The "arrow" is to indicate the direction that
pressure should be applied to the valve, so that the pressure will assist,
rather than oppose the internal spring. In our application, the "pressure",
when the valve is closed, is in the bellows, not the compressor. Therefore,
the "arrow" should point to the bellows. It appears to me that the same
solenoid is also installed in the Electro-Level I systems. If so, they too
may be installed backwards.
Walter, if this helps, and you have further questions, please let me know.
Good hunting.
Scott Shean
Baton Rouge, LA
78 Royale
