Originally Posted by dpinvidic
Curious why folks suspect the dryer.
The wet tank is in front of the dryer, and the pri & 2nd tank are fed by the wet tank.
If the pri tank shows 120psi, that proves the dryer is ok and the wet tank must have 120psi.
In thinking about this more, it is not likely to be a leak, if it was leaking bad enough to prevent reaching 120, it would certainly drop to zero right after the engine was turned off.
A restriction would not prevent reaching 120, it would just take longer than the other tank.
It really sounds more like a sensor problem which could affect both the gauge and the alarm.
The OP really needs to put another gauge on the system to confirm the actual pressure before buying parts and guessing.
Just the opinion of an arm chair quarterback
I tend to agree with you, for all the reasons you mention. The ONLY thing about the entire system that is non-normal is the low reading on the rear tank. It fills, burps, responds to pedal applications, alarm status due to <65psi, etc.
One thing i have learned from this post is that some responses "attacked" me for placing lives in jeopardy bla bla..... As a recently retired captain for a major airline, I made decisions for decades that determined a real problem or a gauge, and I would like to assure them that I would never consider going without full brakes. But in an ideal world, both gauges would read identically. (I have also seen gauges that indicated a perfectly normal condition for a completely inoperative system)
And so now, I will research the sensor by verifying the actual system pressure.