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2003 MONACO DIPLOMAT 40DST FRONT AIR TANK SENDING UNIT


Russgh
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Hi Monacoers, I am new to the group.

I am having trouble with the low air alarm. I discovered the buzzer connector disconnected and reconnected it. It operates normally, beeper & low air light is on until the air pressure reaches around 70 psi. After reaching 120 psi, when I put the transmission in gear, the beeper comes on but not the low air light.  The beeper sound is different than the low air sound. I suspected the sending unit on the front air tank however disconnecting the sending unit does not stop the alarm when the transmission is in gear.  I removed the relay marked Bell-1 in the Monaco 2 box in the left front bay cabinet and everything works as it should i.e. beeper and light on when pressure is below 70 psi, goes off above 70 psi.  The beeper and light do not come on when the transmission is in gear. 

What else does the Bell-1 relay do? could it disable other alarms.

What does the sending unit do on the front air tank, disconnecting it had no effect that I could see?
See photos below. IMG 2122 is the sending unit on the tank. IMG 2125 is the relay that goes in the box on the right of it.
Any help or wiring diagrams would be greatly appreciated.
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IMG_2122.jpg

IMG_2125.JPG

IMG_2126.JPG

IMG_2126 (2).zip

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Russ, I had that issue in 2018 ended up replacing the hydraulic tank and float valve.  After 11 years the tank had a minute leak ,  but the foam float valve also became saturated with hydraulic fluid causing it to drop into the fluid , which the alarm sensed as being low on fluid.  No problem since replacing the tank and valve.

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May I impose on this discussion without distracting attention from the primary question. I know that the experts can answer this off the top of their heads. 
What should the max air pressure be? My pressure guage gets to a high of around 140 at start up and when it recharges on a trip it gets to around 130. 
Is this acceptable? 

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2 hours ago, Rick A said:

May I impose on this discussion without distracting attention from the primary question. I know that the experts can answer this off the top of their heads. 
What should the max air pressure be? My pressure guage gets to a high of around 140 at start up and when it recharges on a trip it gets to around 130. 
Is this acceptable? 

It probably should have been a new topic but a quick answer is that you should have somewhere around 120-125 psi cutoff, normally. Safety valve opens at 150. There is an adjustable air governor to get it down if you so decide. Depending which make you have, there are adjustments described at number of places on the net. If you search for air governor, you might recognize the one you have.

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First my disclaimer. I am not familiar with your coach.

A bunch of things can trip a buzzer. Low oil pressure, (should sound whether in gear or not) low coolant, antenna up, slide out, maybe jacks not fully up.

Typically you would have an idiot light or other indication to tell you what it is complaining about.

Since the air buzzer goes off and it buzzes when put in gear, I would be looking for something besides air pressure. Parking brake alarm should give a visual. Easy to test that one.

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Here is the diagram, i thought it was in the downloads section but didn't see it.

It is a PDF file.  When you open it and zoom in it will be blurry, hit CTRL5 and it will clear right up.  You can do a word search and it will take you through all the hits, once you figure out the right word(s) it makes it easy to follow. 

If you find a specific area you want to keep you can do a print screen and save it too your files.  Alternator connections is a good example.

 

2002 Chassis Wiring Diagram 1.pdf

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