diffrent pressure readings on front & rear air tanks

[mikee409]

Both gauges used to read 125 psi but about 1/2 way thru our trip to Moab the rear started reading about 15 psi less. When the compressor kicks in the both reach 125 psi but as soon as I touch the brakes the rear drops about 15 lbs. and stays there. I crawled under the edge of the rig and can't find any air leaks. There is negligible air loss over night. So what gives? any one ever had this happen? I have a Spartin chassis.
Mikee

[Skip426]

Your air brakes should operate , front; off of one tank, rear : off the other.
Air suspension, and other air operated accessories, ( horns, exhaust brake) , run off one tank .
The air suspension , during it's operation in keeping the coach level in corners could easily deplete the one tank by 15 psi, before the compressor cycles to re-build the pressure.

Getting an air-system diagram for your chassis from Spartan , would be the first step. To find out what systems are operated off the tank in question.
Spartan Motor Home Support
1-800-543-4277
Have your serial number handy.