May 25, 2017
Vehicles with listed GM Gen. 3 6T40 transmissions may exhibit no line rise or low line pressure due to excess wear in the pressure regulator isolator valve assembly. The pressure regulator isolator valve reacts against the pressure regulator valve, controls balance pressure, and dampens and smooths pressure pulses from the pressure control solenoid. Excess wear can lead to undesirable shift operation and burned clutches. Installing Sonnax pressure regulator isolator valve kit 144510-15K restores proper line pressure control for renewed shift feel and performance.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.