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Air Pressure Gauge Issue

I visited my coach today for the first time in a month.  I decided to start the engine and get the air pressure up.  Up until today the process would be as follows-
1. Start engine.
2. Low air alarm becomes audible.
3. HWH travel mode is not illuminated.
4. Front and rear air gauge needles move and then fall back.
5. Use "hi idle" on smart wheel to begin air build-up.
6. Front and rear air gauge needles begin to show building pressure.
7. As pressure builds, front entry step activates and gets pulled up.
8. Low air alarm is silenced.
9. There is the sound of pressure relief which I believe is the air dryer purge.
10. HWH travel mode light illuminates.
All good to go.

Today all went exactly the same except-
1. Rear gauge did not show pressure building.  (The needle did it's typical clockwise move up and then fall back to no pressure with key in accessory position prior to starting)
2. Alarm never silenced.
Note: The HWH travel mode green light did illuminate.
3. I did a cursory ride height visual check at each tire.  All looked normal.
4. I listened for leaks but did not hear anything. May be too noisy where so am parked.  The facility was using their leaf blowers.

I could not spend any more time to diagnose the problem today.  Since the alarm would not silence it makes me think it is not just a bad gauge.

Since I have to travel 30 minutes or so to get to the coach, would someone be able to give me help developing a game plan to figure out what is going on?

Thanks for taking the time to read my post.

-FT
2001 U270- 34'
with Aqua-hot
Travel Safely
Have Fun!!

Re: Air Pressure Gauge Issue

Reply #1 –
01's have an unusual operating system I have seen posted.
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Air Pressure Gauge Issue

Reply #2 –
When I had the same issue last year, it turned out to be the solenoid on the side of the tank. I swapped the wires between the front and rear tank, and the problem went from the rear to the front tank, letting me know it was the issue. Replaced the solenoid (I believe I ordered it from Summit Racing, there is a part number on the solenoid to search) and its been good since.

To check if you have air in the tank versus a bad read, give it time to fill, and then open the drain valve a little. You'll know if you have pressure right away.

MAKE SURE YOU USE SAFTY STANDS BEFORE YOU GET UNDER THE COACH.
Mark & Bev
2001 U295 36' Slide
Cummins ISC 8.3 350HP
Build #5802
Jeep Wrangler Toad

Re: Air Pressure Gauge Issue

Reply #3 –
Thank you Mark.

This is my first coach and it is still new to me.  I appreciate your help very much.  I will look for the solenoid and follow your approach.

Seems there is always something but it has been a lot of fun regardless.

-FT
2001 U270- 34'
with Aqua-hot
Travel Safely
Have Fun!!

Re: Air Pressure Gauge Issue

Reply #4 –
Mark, did you mean sending unit instead of solenoid?  My coach occasionally has shown zero pressure in one of the brake tanks...it's an intermittent poor connection with the pressure sending unit....it fixes itself in a few miles.  Confirmed at a rest stop by opening the drain valve on each tank momentarily to check for pressure one time it stayed at zero for a while.  Agree....safety stands first unless you have remote air tank drain valve handles like Roger and others have retrofit....on my bucket list.

Also, got a Summit part number???  Woody.

Quote from: MarkC –
When I had the same issue last year, it turned out to be the solenoid on the side of the tank. I swapped the wires between the front and rear tank, and the problem went from the rear to the front tank, letting me know it was the issue. Replaced the solenoid (I believe I ordered it from Summit Racing, there is a part number on the solenoid to search) and its been good since.

To check if you have air in the tank versus a bad read, give it time to fill, and then open the drain valve a little. You'll know if you have pressure right away.

MAKE SURE YOU USE SAFTY STANDS BEFORE YOU GET UNDER THE COACH.
2001 4010 U320 build #5865 "Bluto-d-Bus" since 09/18
2006 Honda Element ESP Toad
Full timing since 2016 in Western MT
Copilot: Sitka
1975 GMC 260 Avion: sold

Re: Air Pressure Gauge Issue

Reply #5 –
Yes, Thank you, Sorry for the bad information.....I was brain dead. 
It is the sending unit on the end of the tanks that sends the pressure reading to the gauges, not a solenoid.  That was what was my issue, gauge said 0 but tank did have pressure.
I believe this is fairly common to go bad, I have read several threads where others have switched to mechanical gauges.
Mark & Bev
2001 U295 36' Slide
Cummins ISC 8.3 350HP
Build #5802
Jeep Wrangler Toad
 

Re: Air Pressure Gauge Issue

Reply #6 –
Thanks again Mark.

Really appreciate your help.

-FT
2001 U270- 34'
with Aqua-hot
Travel Safely
Have Fun!!