In ZF5HP19 units, the pressure modulator valve train controls accumulator back-pressure relative to load and is subject to significant wear due to constant motion under normal operating conditions. Excessive bore and valve spool wear will likely cause poor or no line pressure rise. Poor line pressure rise is indicated by flare upshifts or slip/chatter in reverse. Other symptoms such as softening and lengthening shifts with rising temperature and clutch distress may be present. Installing Sonnax oversized pressure modulator valve kit 85755-03K can restore proper functionality to the entire bore and valve train.
OE valve spool diameters must match dimensions noted in the illustration. This kit cannot be used to repair valve bodies with valves of other sizes.
A vacuum test at the ports indicated fail to hold at least 18 in-Hg