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Old 06-25-2019, 04:18 PM   #1
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Problem with low pressure beeping?

My bus maintains 120 PSI while driving with no apparent problem, although if I let the bus sit for a couple of days the pressure drops to 30 (haven't found any leak externally yet although I haven't spent much time trying) so I obviously have a leak somewhere.

When I'm driving, sometimes the low-pressure beeping comes on for a good while even though the gauge is showing 120. At least I think it's the low-pressure gauge since it's making the same noise (everything on the dash is in normal range).

I'm planning on taking my bus to the mechanic ASAP to have the leak looked into so I'll have them look at the beeping problem too, but I was wondering if anybody here had any insights into what might be causing it. Maybe the beeper is the leak?
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Old 06-25-2019, 06:39 PM   #2
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Wouldn't Schroedinger's cat cat just
Laaaaaaaaaaaaf
If that were the case..?
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Old 06-25-2019, 06:43 PM   #3
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Wouldn't Schroedinger's cat cat just
Laaaaaaaaaaaaf
If that were the case..?
It took me a while, but I get it.
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Old 06-25-2019, 06:47 PM   #4
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Ah, Hell, not that long!
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It took me a while, but I get it.
Does that even things up some, due to my earlier Anabaptist gaffe..?
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Old 06-25-2019, 06:59 PM   #5
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Ah, Hell, not that long!Does that even things up some, due to my earlier Anabaptist gaffe..?
To be fair, that might have been my gaffe. I don't actually know whether the workers in the Jayco video were Amish or Mennonite - and I don't think either group would have appreciated the "on speed" remark.
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Old 06-25-2019, 07:09 PM   #6
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My bus maintains 120 PSI while driving with no apparent problem, although if I let the bus sit for a couple of days the pressure drops to 30 (haven't found any leak externally yet although I haven't spent much time trying) so I obviously have a leak somewhere.

When I'm driving, sometimes the low-pressure beeping comes on for a good while even though the gauge is showing 120. At least I think it's the low-pressure gauge since it's making the same noise (everything on the dash is in normal range).

I'm planning on taking my bus to the mechanic ASAP to have the leak looked into so I'll have them look at the beeping problem too, but I was wondering if anybody here had any insights into what might be causing it. Maybe the beeper is the leak?

If it takes three days to leak down to 30 psi from 120 psi I would not be worried. It is normal. After a few days parked, you should expect the pressure to be down and have to let the system build pressure when you start it up again.

"est air leakage rate: With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop. The loss rate should be less than 2 psi in 1 minute for single vehicles "
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Old 06-25-2019, 07:52 PM   #7
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120 PSI to 30 in a couple days is fine. Mine leaks that much overnight. ... actually more like a couple hours.


The low pressure sensor - are you getting the light too? I've had a lot of trucks that use the same beeper for low oil pressure and over temp (and with many newer trucks, low coolant). Check the wires to the air pressure sensor, they may be loose or shorted. The sensors can fail with age.
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Old 06-25-2019, 08:23 PM   #8
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120 PSI to 30 in a couple days is fine. Mine leaks that much overnight. ... actually more like a couple hours.


The low pressure sensor - are you getting the light too? I've had a lot of trucks that use the same beeper for low oil pressure and over temp (and with many newer trucks, low coolant). Check the wires to the air pressure sensor, they may be loose or shorted. The sensors can fail with age.
There's no light on the dash when the beeping happens. The gauges for oil pressure and temp seem fine (although I'm not sure about that).

That's my fear, that the beeping is indicating some other problem than air pressure.
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Old 06-25-2019, 08:27 PM   #9
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You should be getting a light if it's beeping for some other reason - a yellow check engine light or a red shut down now light. Assuming these illuminate briefly during startup (as they should) and you're presumably not seeing them as you drive, I would lean towards a faulty low air sensor/circuit.
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