February 21, 2013
Common problems in vehicles with GM 4L80-E and 4L85-E transmissions include uncontrollable line rise (upward of 500 psi), high line pressure in Reverse, broken direct clutch drums and/or broken cases. These problems can be caused by excessive EPC torque signal pressure. Sonnax self-regulating boost valve kit 34200-10K eliminates these problems by limiting EPC pressure.
Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.