Suddenly, the low air pressure alarm on my 94 Regency with the 300 HP Cummins will not stay off after pressure has reached normal levels in both tanks (according to the dash gauges). After the coach has been sitting and air pressure has bled off, the beeping alarm comes on at the start of the engine and shuts off for a minute or two as pressure starts building. But it now comes back on and stays on even after pressure has peaked at about 80-90 psi. When driving, the alarm comes and goes as if there might be a loose connection --- but where do I look? Also, the audible alarm seems to be linked to a red warning light on the dash labeled "Low Air/ Tank 1" which comes and goes with the audible alarm. There is a space for a red warning light for Tank 2 that must be burned out. Could the burned out light be causing the problem? I don't remember if the burn out is recent or not.

On the front firewall above the generator, there is a manifold with two wires labeled "Air 1 & 2" attached to pressure sensors but with the alarm beeping --- the removal of the these wires causes no change even if I ground them.

Help, Help!!!!

My preparation for the summer season keeps getting complicated by new problems. This year it seems like every time I start it --- something new quits working. I guess this is typical for old Barths --- they force more bonding!!!???

Any help will be greatly appreciated,

Frustrated

Did you say "peaked at about 80-90 psi"? My understanding is that your 'peak' should be around 120. My audible alarm comes on if the air drops to somewhere in the 60-75 psi range. Don't recall exactly.

Sounds like the alarm itself isn't the problem. Sounds more like the cutoff limit for the governor isn't correct, or you have some sort of major leak.

The Florida CDL book (other states have similar references) gives a pretty good writeup for air systems. http://www.lowestpricetrafficschool.com/handbooks/cdl/en/5/1 is a pretty good reference.

Mike

"even after pressure has peaked at about 80-90 psi. When driving, the alarm comes and..."
Yeah; my Spartan 325 Cummins peaks, and stays, 110-115 psi; when pumping up, the alarm ceases just before the red lights (tanks 1 & 2) go off, between 70 & 80 psi. Perhaps the red light is a function of the (low) pressure, since it comes and goes with pressure. I believe Relative is correct: the problem is not in the alarm itself. Note: my Parking/Emergency brake won't release below 75 psi, so I figure 70-80 psi is when they will automatically apply.

Frank,

Not only does your air pressure seem low, but I have also had problems with my pressure alarm coming on due to a poor electrical connection. It caused the alarm to see the pressure as lower than it was and kept the alarm on. It was the result of a faulty soleniod that powered much of the dash electricity.

Bill G

What chassis do you have?

Mike

I suspect that Bill G is on the right tract for me also but that electrical panel under the driver's side window is a real challenge.

My unit has the Spartan MM chassis and I was wrong about the peak air pressure. I was trying to recall from memory and at my age, that's risky. The peak air pressure is about 110 psi for both the front and rear tanks. Everything seems normal except that the audible alarm will not turn off. I also just checked the light bulbs in the red warning lights and they are all OK. Something is not sending the right signals.
Thanks for the feedback!!

Frank, 80-90 is NOT PEAK!!!

Your governor is either set too low or is failing. The correct psi peak is between 110 and 125.

That being said, the most likely place to install a low air psi switch is on the gov itself. These are usually one wire and they ground out to complete the circuit and turn on your light and buzzer.

Look around the air compressor for the gov. If you see any wires going to the compressor then that is your low psi switch.

Now, lets face the fact that your engine is mounted in the rear. Why would someone run a wire all the way back to the engine for a dash light on the front? They just do, but that doesn't mean that yours IS mounted back there, it's just were they normally put it.

If no wires are found back there then trace out the air psi gauge airlines - these lines will usually be run to an air manifold. You will find the switch located on a manifold or junction. Do not mistake the brake light switch for the low psi switch - if you disconnect the wire and the light/buzzer is still working then you are probably on the brake light switch.

A lack of air applies these switches, any restriction/kinks in the line will cause a lower reading.

This switch is mounted in the psi side - bleed off all air before removing - start up coach with the switch out to make sure air is going thru the line. Shut off to install.

This should go without saying, but still I feel compelled to say it: Just make sure you're not removing an oil psi idiot light sender switch before you start up the coach!