No answers to Air brake indicator problem +

[BlueLine]

I posted on the Freighliner forum with no answers or responses to a problem I've been noticing on my 1999 Winnebago 34V DP on a Freightliner frame and a 5.9 Cummins ISB engine. My 2 air pressure gauge indicators are a Red and Green needle on a Freightliner Dashboard. They both initially indicate 120# after start up however after about 10 minutes into the trip the red bleeds down to 100# but quickly recharges back to 120# to match the green. After shutdown the red needle fell to zero in about 10 minutes but the green stayed up for about 24 hrs. I soaped every line that I could find at home and found no bubbles, I even soaped the air bags front and back. The next time out the gauges stayed relatively stable and matched for about 3 hours of travel. After shut down the both bled down uniformly over 24 hrs, I thought the gremlin had been taken care of. My next time out and about 10 minutes into the trip it all started again, the miss match and pump up continuously for a 3 hour leg. During the trip the Red stays matched for about 10 minutes. I'm assuming HWH color coded all the lines and I paid close attention to all the RED tubing and fittings I could find. The only fitting I may have missed was the under dash one at the rear of the gauge itself. Does anyone have a clue as to where I should crawl and look, or am I looking at the wrong things. In all the Freighliner electronic dash board has shown me some weird indications, I have to use the GPS for speed indication because the speedometer only works when it wants to, most of the time it creeps right up to the top of the scale and stays and the trip odometer indicator clicks off mileage like double time. The Oil pressure floats in an annoying manner. I believe the Air pressure however is mechanical and the others are computer but I'm not sure.

[RJay]

gcipra,
I don't have a freightliner chassis but have you tried to call your local freightliner service center?

[BlueLine]

Quote:

Originally Posted by RJay gcipra, I don't have a freightliner chassis but have you tried to call your local freightliner service center?

No I have not, I'm trying to re register the chassis under my name with Freightliner so I can get access to them on line. Do you have a Number?

[smlranger]

You can get technical support from the Freightliner Custom Chassis folks at 1-800-FTL-HELP. Call them and have the last six characters/digits of your chassis serial number ready.

It is a long shot but Freightliner had some problems with the VDU or VDC (vehicle data unit/computer) in the engine compartment. Many of them had some cold solder joints causing all sorts of weird dash instrument display problems. Many of us with these affected VDU's removed them and re-soldered the joints, fixing the issues. If FL suggests the VDU may be your problem, send me a PM with your email address and I can send the article detailing how to do the repair. A new VDU is about $420.

Another thing to check is all the grounds. A loose ground can cause all sorts of issues.

Also, FYI, in NC you are not too far from the best Freightliner Custom Chassis service there is. The factory service center is off I-85 in Gaffney, SC and provides great service at reasonable rates.

[BlueLine]

Thanks for the direction. I'll check what grounds I can find tomorrow, I know of One up front near the HWH system, one at the battery tray and one under the dash. I will also call the 800 #. My e-mail is: flyharley@inteliport.com

[OneRVer]

Your air gauges are pneumatic. Can you hear an air leak under your dash?

[BlueLine]

Cant hear any air leaking under the dash. Did call Freight Liner today, they suggested leaving the Park brake on, but have someone depress and continue to hold the foot brake while I soap the connecting braided hoses on the rear brakes. The tech said the hoses are known to deteriorate inside the braiding. This will be tomorrows endeavor. They also told me that the tubing going to the back side of the dash goes to a manifold and is processed by the computer. He suggested I check for tight clean grounding. Since my dash panel is displaying some erratic readings it could be a bad ground, or a loose or corroded plug connector in the back of the dash display unit. I'm working on both.

[OneRVer]

Quote:

Originally Posted by gcipra Cant hear any air leaking under the dash. Did call Freight Liner today, they suggested leaving the Park brake on, but have someone depress and continue to hold the foot brake while I soap the connecting braided hoses on the rear brakes. The tech said the hoses are known to deteriorate inside the braiding. This will be tomorrows endeavor. They also told me that the tubing going to the back side of the dash goes to a manifold and is processed by the computer. He suggested I check for tight clean grounding. Since my dash panel is displaying some erratic readings it could be a bad ground, or a loose or corroded plug connector in the back of the dash display unit. I'm working on both.

I guess that shows the age of my MH. My air lines are connected right at the gauge. Wish they would keep stuff simple.