Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: DavidS on September 26, 2019, 02:21:32 pm

Title: 02 U320 Air gauge stopped working
Post by: DavidS on September 26, 2019, 02:21:32 pm
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.
Title: Re: 02 U320 Air gauge stopped working
Post by: Roger & Susan in Home2 on September 26, 2019, 02:57:16 pm
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... (https://www.vdo-instruments.com/instruments/by-type/air-pressure/vision-black-150-psi-mechanical-air-pressure-gauge-front-12v.html)

Rear
Vision Black 150 PSI Mechanical Air Pressure Gauge, "Rear", 12V | Air... (https://www.vdo-instruments.com/instruments/by-type/air-pressure/vision-black-150-psi-mechanical-air-pressure-gauge-rear-12v.html)

Unlabeled
Vision Black 150 PSI Mechanical Air Pressure Gauge, 12V | Air Pressure | By... (https://www.vdo-instruments.com/instruments/by-type/air-pressure/vision-black-150-psi-mechanical-air-pressure-gauge-12v.html)


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.
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on September 26, 2019, 04:06:13 pm
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
Title: Re: 02 U320 Air gauge stopped working
Post by: Michelle on September 26, 2019, 04:10:19 pm
"Blue Module" Failure (https://www.foreforums.com/index.php?topic=15135.0)

Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on September 26, 2019, 04:36:42 pm
"Blue Module" Failure (https://www.foreforums.com/index.php?topic=15135.0)
Your the best!! ^.^d
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on September 26, 2019, 09:10:29 pm
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?
Title: Re: 02 U320 Air gauge stopped working
Post by: wolfe10 on September 26, 2019, 10:04:42 pm
David,

Should be able to trace it from the number on the wire along with your wiring diagram.
Title: Re: 02 U320 Air gauge stopped working
Post by: Roger & Susan in Home2 on September 26, 2019, 10:06:11 pm
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.
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on September 26, 2019, 10:42:39 pm
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
Title: Re: 02 U320 Air gauge stopped working
Post by: rbark on September 26, 2019, 10:53:45 pm
Thinking that's for the Hadley's (think horns)
Title: Re: 02 U320 Air gauge stopped working
Post by: Journey, Roam, Explore on September 27, 2019, 07:40:54 am
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.
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on September 27, 2019, 09:40:19 am
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 !!
Title: Re: 02 U320 Air gauge stopped working
Post by: jbeem on September 27, 2019, 09:53:46 am
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.
Title: Re: 02 U320 Air gauge stopped working
Post by: Michelle on September 27, 2019, 09:54:33 am
Gotta find this blue box first.. its illusive !!

Pic of one (not in-situ, unfortunately) in this thread.  air gauge on 2003 U320 (https://www.foreforums.com/index.php?topic=23428.0)
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on September 27, 2019, 10:43:25 am
Pic of one (not in-situ, unfortunately) in this thread.  air gauge on 2003 U320 (https://www.foreforums.com/index.php?topic=23428.0)
I found that pic yesterday.. it is not under their but I was in a hurry last night and I spent 10 min digging.. I would have thought 10 min would have been enough but I digress  :'(
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on October 06, 2019, 08:34:27 pm
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
Title: Re: 02 U320 Air gauge stopped working
Post by: Michelle on October 06, 2019, 08:37:05 pm
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?
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on October 06, 2019, 09:22:17 pm
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.
Title: Re: 02 U320 Air gauge stopped working
Post by: Roger & Susan in Home2 on October 06, 2019, 10:12:05 pm
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
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on October 06, 2019, 11:55:42 pm
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.
Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on October 11, 2019, 11:01:18 pm
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 ..

Title: Re: 02 U320 Air gauge stopped working
Post by: DavidS on December 06, 2019, 09:52:26 pm
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.. :))