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Topic: 02 U320 Air gauge stopped working (Read 1101 times) previous topic - next topic

02 U320 Air gauge stopped working

Not realizing that the air gauges are the brakes/ Hwh but mainly for the air brakes (makes sense now)

Never thought about it and always understood it to be Ride height pressure (which is a part of it).

Lost the function of the front air gauge

Anyone know where the Magic Box that sends the info might be located? Also is their a transducer/ solenoid after or before.. I dont have my folder with me right now to look at the schematic..

Thanks Craneman and Juicesqueezer for the help so far.

Re: 02 U320 Air gauge stopped working

Reply #1 –
If your pressure gauges are not working then it is the pressure transduce at the tank, the wiring to the blue or gray box, something in the blue box, the wiring to the gauge from the blue box or the gauge.  The most common thing is the blue box which is apparently not replaceable or repairable.  What most of us have done is replace the gauges with direct read mechanical gauges with an air line h (1/8" or 1/4") connected to the tanks where the pressure transducers were to the tank.

If it is the blue box or anything between that and the pressure transducer that has failed you may be getting a warning chime. It may take both to fail before the chime begins to sound.  This is the low pressure alarm.

A direct read gauge is nice because it shows pressure whether the ignition is on or not.  I added a third pressure gauge to monitor the HWH tank pressure as well.  And at night the lighting is better than the OEM gauges.

Front
Vision Black 150 PSI Mechanical Air Pressure Gauge, "Front", 12V | Air...

Rear
Vision Black 150 PSI Mechanical Air Pressure Gauge, "Rear", 12V | Air...

Unlabeled
Vision Black 150 PSI Mechanical Air Pressure Gauge, 12V | Air Pressure | By...


Shop for price and shipping cost.

The install kits are for cars and did not have enough air line,  the parts are common and easy to find.  Use brake air line and DOT rated fittings for the tubing.

Re: 02 U320 Air gauge stopped working

Reply #2 –
Ty.. made my way down their to get my schematics... see they are connected to the tank directly.. will check it out and go from there.

I will update the thread once I figure it out ^.^d

Re: 02 U320 Air gauge stopped working

Reply #3 –
"Blue Module" Failure

Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

Lifetime Escapees' member SKP 82766
Former 1999 30IB Lazy Daze (2000-2004)
Former 2003 U320 (2004-2016)
Former 2017 LTV Unity (2017-2023)
Shopping for our next coach

Re: 02 U320 Air gauge stopped working

Reply #5 –
No blue box/grey or any other color I can find

I did find this but I am not sure what it goes too? it has a green wire on it and the guage also has a green wire but I couldnt trace it as it was in a huge bundle.. anyone know what its for?

Re: 02 U320 Air gauge stopped working

Reply #6 –
David,

Should be able to trace it from the number on the wire along with your wiring diagram.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 02 U320 Air gauge stopped working

Reply #7 –
Those are for the horns?  Follow wires back from the dash gauges. They should go to a gray or blue box.  On this drawing it is right in the middle next to the tach and speedo.  Lots of wires in and out.

Re: 02 U320 Air gauge stopped working

Reply #8 –
That dash has a ton of wires.. I think if I stripped the coach of copper I could buy me a new one..  ;)

Thanks Roger.. Answers that

Re: 02 U320 Air gauge stopped working

Reply #9 –
Thinking that's for the Hadley's (think horns)
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: 02 U320 Air gauge stopped working

Reply #10 –
David, sounds like the best option if you have a issue with the blue module is to bypass it like Rodger did. Wonder why Foretravel didn't just do that in the first place.  Sometimes I think someone just over thought these things. Hope you get it sorted.
'99 U320 40 WTFE
Build #5462,
1500 Watts Solar 600 amp Victron lithium
2012 Jeep Grand Cherokee Overland Hemi
Instagram bobfnbw
Retired

Re: 02 U320 Air gauge stopped working

Reply #11 –
Quote from: Bob and Julie –
David, sounds like the best option if you have a issue with the blue module is to bypass it like Rodger did. Wonder why Foretravel didn't just do that in the first place.  Sometimes I think someone just over thought these things. Hope you get it sorted.
Gotta find this blue box first.. its illusive !!

Re: 02 U320 Air gauge stopped working

Reply #12 –
David, is the rear gauge still working?  If it is (you only mention the front gauge not working) then I would say it isn't the magic box but the sender on the tank or the gauge itself.  Have you tried switching the wires behind the gauge so that the front is reading the rear and rear the front.  If after switching wires your front gauge starts to work then it is probably the sender on the tank or a bad wire between the sender and gauge.  Don't forget to switch wires back afterwards.  Mine were reading the wrong tank for a long time.
2002 36' U270 Foretravel

Re: 02 U320 Air gauge stopped working

Reply #13 –
Quote from: DavidS –
Gotta find this blue box first.. its illusive !!

Pic of one (not in-situ, unfortunately) in this thread.  air gauge on 2003 U320
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

Lifetime Escapees' member SKP 82766
Former 1999 30IB Lazy Daze (2000-2004)
Former 2003 U320 (2004-2016)
Former 2017 LTV Unity (2017-2023)
Shopping for our next coach

Re: 02 U320 Air gauge stopped working

Reply #15 –
I am not able to locate this piece.. I have searched all over inside the dash.. anywhere else you would think.. cant follow the wires as they go through bundles.

Any suggestions on where everyone else that has had this issue located this part?

Also I find it strange that when I replaced the rear axle seal this stopped working.. I had to disconnect the rear brakes but everything is working but the gauge.. just seems strange.. I am kinda thinking it is not the blue box

I did swap the plug from the rear to the front and it did the same so it is the signal..

Can someone send me the Emergency Foretravel number.. might call them tomorrow

Re: 02 U320 Air gauge stopped working

Reply #16 –
Is it possible the PO had the module fail before you bought the coach and a different scheme was implemented?  Any records on the coach service?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

Lifetime Escapees' member SKP 82766
Former 1999 30IB Lazy Daze (2000-2004)
Former 2003 U320 (2004-2016)
Former 2017 LTV Unity (2017-2023)
Shopping for our next coach

Re: 02 U320 Air gauge stopped working

Reply #17 –
Quote from: Michelle –
Is it possible the PO had the module fail before you bought the coach and a different scheme was implemented?  Any records on the coach service?

I can ask him as I know him personally.. never thought of that.

Re: 02 U320 Air gauge stopped working

Reply #18 –
If your gauges have plugs on the back with a wire connection then they are the electronic gauges.  I think the plugs have a red retaining clip. The wires from the air gauges, front and rear, connect to the box.  The box is supplying a five volt signal to the pressure transducer at the tank which is a variable resistor.  The return voltage is 0-5 volts which is interpreted by the box and a signal is sent to the gauge.  If you changed wires from one air gauge to the other and the readings switched with it then could be the transducer or a wire error between the transducer and the box.  If it is reading zero and the dinger is dinging the box is interpreting what it sees as zero voltage (pressure) or an open circuit.

As I recall the box is about 5x5".  Mine is gray.  Buried in the wire mess to the right of the gauge cluster.  If it is gone then have all the gauges been replaced and rewired? 

Did you find the dinger and add a switch to silence it

Re: 02 U320 Air gauge stopped working

Reply #19 –
I will dig again and able check 1 last time.. the finger was unplugged but I plugged it back it it makes a small ding but nothing else..

. I would think their would be air lines coming in somewhere that go to the blue/gray box.

Re: 02 U320 Air gauge stopped working

Reply #20 –
Called Foretravel today and I do not have a Blue or Gray box.. but a black box .. it is a VDO converter box approx size is 3x6.. I will take a pic later .. think I have narrowed it down to the sender at the tank. Will change this and will post my result.. but just wanted to update as I have looked for this blue box for a while off and on.. didn't exist ..

Re: 02 U320 Air gauge stopped working

Reply #21 –
Ill add the fix to this finally... Dont laugh.. ^.^d

Bought a new solenoid from VDO to replace the one on the front tank.. That is where we narrowed the problem down to...

Solenoid didnt work as it is different connections so I took the other off to see if I could find some numbers on it... tapped it on my hand a couple times and shook it.... reinstalled and is working now.. Something stuck inside I guess but nothing was working and I swapped the plug on the rear a couple times so it wasnt the plug... It fixed itself .. Sometimes it works that way and I have learned to take it and move on and not dwell on it.. :))