Air Gauge type on 2000 Itasca Horizon

[tennsmith]

I am having trouble with what appears to be an intermittent gauge reading of pressure in my rear/secondary air tank.  I am wondering if the gauge is a mechanical one, or electrical with a transducer mounted remote from the gauge head.  Here is what happens.  On a cold crank after weeks of setting, the primary tank air gauge responds normally, rising to compressor cutoff value.  The secondary gauge, however, tracks to about 45 psi and then hangs there.  From then on, it proportionately moves with the primary gauge, but reading about 30 when the compresor cycles on (100 psi on primary) and about 45 when the compressor cycles off (about 125-30 psi on primary)  I thought I had a check valve problem, consulted a lot of internet posts on the subject and someone asked me if my air dryer was popping off as it should...so I go back to the motorhome, turn on the switch key, and both gauges jump to 100 PSI and when I start it up, they both track to compressor cutoff.  Until the next bleed down of pressure, they work as they should.  This has happened twice within the past month.  I think it's a gauge problem, and more specifically, a transducer problem IF the gauge is electric, and since it doesn't respond until the switch is turned on...I assume it is.  I am just looking for affirmation of gauge type and to see if anyone else has experienced this problem and can shed any light on it. 

tia,
tennsmith
Huntsville, AL

 

[John Canfield]

I think I remember someone here having air gauge problems but it's a distant memory. Call Freightliner tomorrow,  those guys are really helpful.

 

[Jim Godward]

2000 era Freightliner chassis did have problems with the air gauges.  The problem is in the box in the engine bay where the air hoses are couple to the electronics.  The pressure traducers may have developed intermittent connection with the circuit board thus causing the intermittent gauge readings.  The solution is to remove the box, open it and inspect for these cold solder joints and re-solder them.  Then reseal, remount and verify the repair.  The alternative is to have the box replaced, ~$600 for the box and a couple of hundred for the labor.
I and several others wrote a repair procedure that corrects the problem if that is what you have.  It can be found on the Newmarowners list, https://groups.yahoo.com/neo/groups/NEWMAROWNERS, on Yahoo, and on the diesel RVs list or if you send me your email address I can send a copy to you.  Send the address to ac7po at arrl.net and I will get  a copy sent in a day or so.  I would promise sooner but I currently have some medical issues and may not get on the computer for a day or so.  That is rare but it does happen.

I found it on the following site in the files section of the FCOC list and here is the URL to the file.
https://xa.yimg.com/df/FCOC/Repair+FL+VDU.doc?token=oprJPshKZ_NJBOZfbPM-efPQslcBjXT54ypqkJMYHHoiMJl-xBdG3tixdczv_f_xIP5tgtGMKtbRBEJ7Lj7VvKKSSu1_3E0IvYsvgDa0KBjLgsRf&type=download