[vettestr]

Hey GF,
The motor only runs when a low pressure sw. signals a run command and then turns it off when accumulator reaches set point. All of these commands are internal and done via a grey switch. The first generation units had issues that were corrected with new designed sw., the easy way to tell generation of unit or if upgraded is to look for the GREY pressure sw. on master cyl.
This unit is small and compact with Hyd. motor hanging below the master cyl but we mount the motor and the master cyl unit side by side for ease of installation.
The Hydraboost or unit that is run from the PS pump was large to huge by comparison to the Power Master unit. The PM unit also has an aluminum master cyl for weight savings. The Hydra system always seemed to leak, for me at least and I just got tired of it always marking its spot. The way you new you were low on fluid is when it quit dripping!!