Air Brake Problem

If it's the sending unit as I previously described, mine was in the back driver's side compartment. The unit is easily installed although I had a Freightliner shop do it. I paid about $300 - $350 out the door and, if I remember right, the unit alone was about $175 . Don't hold me to those numbers... just shooting from memory.

sambar wrote:
Thanks for the info. We are running on a Freightliner Chassis. Happy to hear the solution may be simple.
Any details on how simple the solutions may be to self-install and their location?

Call Freightliner Customer Assistance, 1-800-385-4357. Have the VIN number handy. They should be able to tell you if there is your coach is subject to the wiring issue I mention earlier.

If it is a wiring issue, they should be able to tell you how to get the new cables. The hardest part about installing them is removing the front of the dash to get to the back of the gauges.

Tom

Moved from Forum Technical Support

If the alarm comes on and you actually have a lose of air, the brakes should come on automatically... since they are not it's a electrical problem. Could be a bad sender, poor ground, or a wiring harness problem.

With engine running go outside an listen for the drier to pop open .It should close pretty rapidly( with in few seconds) with no air loss at outlet on drier .If drier was changed an filters not seated corectly the small one inside might have been damaged an small piece gotten it the relief valve .As others said if it is a instant up an down reading it will be as they said. Do find problem before driving .

Thanks for the info. We are running on a Freightliner Chassis. Happy to hear the solution may be simple.
Any details on how simple the solutions may be to self-install and their location?

Does the gauge come back up slowly or pop right back up? If it pops right back up, look at the sending unit for the gauges. Had to replace on my Freightliner.

Could be a wiring issue. Yours is a Spartan chassis, I believe, so I'm not sure if the following is applicable.

In 2007- 2008, many coaches on Freightliner chassis exhibited the symptoms you describe, even with both pressure gauges bottoming out and oscillating up and down. Clearly not really low air, since the parking brakes did not apply.

According to the Freightliner bulletin on the issue, the problem was caused by faulty wiring between the gauges. and they produced a new set of cables that fixed the problem.

Tom