MyRVButler

Well, I keep performing COLA Brake Test every time I fire up.  After pop off, I depress service brake, turn off motor, release Spring Brake and watch the guage, it drops way more than 3lbs.  A couple secs later I hear air expelling, like I'm lifting my foot but I'm not, thats what I mean by the "pedal drop".  Applying further just increases the rate of air psi loss.  Maybe leak at air relay, thats the valve assembly behind pedal assembly, on exterior firewall in front cap. 

Agreed.  No air leaks when coach is static after it pops off.  Its only with pedal apply, and the pedal feels weird, soft and it kinda drops when you give it a firm press so has to be one of the chambers blowing out.  Chambers aren't that pricey, MGM brand common at my local RV chassis shop. 

I'm experiencing a leak in the rear air brake chambers that looses PSI with service brake pedal applied (air suspension stays fully inflated only the rear air tank that leaks).  In other words, applied air brake system leak, it's expelling too much PSI when pedal is depressed.  I guess over time if the brakes aren't used for a bit the bladder inside chambers can deteriorate and leak? Matt