Low Air Alarm

[dennis45]

Maybe it's a full moon or something but I'm being plagued with crazy gauges lately. First my house tank gauges (which miraculously cleared itself) and now this.

My 2003 DS is on a Spartan Chassis.
Yesterday on the way back home I got low air alarms on both gauges. Both dropped visibly into alarm status for a minute or so and then went right back to 120+- psi and all was good. Down the road a while, and same thing. Off and on the whole ride home.

I know for sure its not a low air issue. Definetly a Guage problem.
At the same time I get the low air, my Fuel Guage also drops from full (had just filled with fuel earlier) to under 3/4. When the LA clears the fuel Guage goes back to normal also.

Would like to hear from anyone who has experience with this system.

Just to make sure my day was not going to improve, the engine water pump springs a leak. Hi Ho, Hi Ho, off to work we go.

[tom chelbana]

We have a 04 Essex with a Spartan Chassis and had the same problem. Our problem was just on gauge and when I called Spartan they it was most likely the air pressure sender on the back side of dash outside. They suggested I switch the sender around and see if that made the front air gauge work and it did. In our case it was the air pressure gauge sender on the back side of dash gauge set. Would suggest a call to Spartan 800-543-4277.

[USMCRET]

On a recent trip to the Spartan factory I noted one of my tank gauges was dropping completely off for a second or two and then returning to normal. They replaced the sending unit for that tank and solved the issue.

It's odd that all three of your gauges would act up that way. Did you notice anything going on with your transmission pad? The gauge cluster and transmission pad all share a common ground.

At any rate, I agree a call to spartan is in order. They are a first class operation and are very helpful.

[Sky_Boss]

Did you try the Microsoft Solution? CTRL-ALT-DEL? LOL

Try unplugging the Speedo panel. While I don't if there is a direct correlation with the air gauge I've seen it fix a couple unexplainable issues with the instrument cluster.

Can't hurt.

[JFXG]

Dennis.... Your problem is a failure in the Vehicle Data Computer (VDC). I would get the flipping gauges, 0 to 130 instant changes, low air aural alarm simultaneous with 130 psi on the gauge, etc., etc. This is a known issue, requires replacement of the VDC ( a smallish unit about the size of a paperback book, with both electrical and compressed air connections). I ran into it a couple of years ago, as have numerous others. On my FL chassis with Cat the fix was a few hundred, iirc. Other chassis/engine combos may have different labor charges. My service contract covered it without question.


John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
NHSO RVM103

[Sky_Boss]

Originally Posted by JFXG

Dennis.... Your problem is a failure in the Vehicle Data Computer (VDC). ...

Where is the VDC located?

[JFXG]

Sky Boss, in my coach the VDC is mounted on the sidewall of the engine compartment, on the right-hand side, rather deep into the compartment. I have a side radiator (left side), but it's still a rather awkward reach from the rear, and a rather awkward reach from the bedroom access hatch. My VDC is a medium gray plastic box, and you'll see some electrical connections, and also red and green air connections.

I have no knowledge of the placement in other coaches / chassis.


John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
NHSO RVM103

[dennis45]

Originally Posted by JFXG

Dennis.... Your problem is a failure in the Vehicle Data Computer (VDC). I would get the flipping gauges, 0 to 130 instant changes, low air aural alarm simultaneous with 130 psi on the gauge, etc., etc. This is a known issue, requires replacement of the VDC ( a smallish unit about the size of a paperback book, with both electrical and compressed air connections). I ran into it a couple of years ago, as have numerous others. On my FL chassis with Cat the fix was a few hundred, iirc. Other chassis/engine combos may have different labor charges. My service contract covered it without question.


John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
NHSO RVM103

I contacted Spartan and they believe, and I tend to agree, that the problem is a bad ground. The air sensors and fuel gauge use the same ground and when I get the low air alarm, I also see the fuel gauge drop. To me this is an indication of a ground issue between the two devices.
Spartan sent me Instrument and Gound drawings which will help in my search but I've got a water pump to deal with first before I can start the engine.
Thank you for your comment, if tracing the grounds fails, I'll look at the VDC.

[dennis45]

Originally Posted by JFXG

Sky Boss, in my coach the VDC is mounted on the sidewall of the engine compartment, on the right-hand side, rather deep into the compartment. I have a side radiator (left side), but it's still a rather awkward reach from the rear, and a rather awkward reach from the bedroom access hatch. My VDC is a medium gray plastic box, and you'll see some electrical connections, and also red and green air connections.

I have no knowledge of the placement in other coaches / chassis.


John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
NHSO RVM103

This thought just occurred to me.
You guys have Cat power. I believe Cat calls it a VDC. Cummins uses an ECM, (Engine control Module). Same S$&@, different pile?

[JFXG]

Dennis....
1) If Spartan says ground, then your first shot should be ground. When my VDC failed, I had no erratic fuel gauge, and the VDC was a known issue in FL/Cat applications.

2) VDC = ECM? Possibly, but there may be other controlled functions as well. If you're in contact with Spartan, they'd be the ones to ask.


John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
NHSO RVM103