September 30, 2005
The shift pressure control plunger valve in Aisin AW 55-50SN and 55-51SN units utilizes shift control solenoid fluid pressure (SLS) to regulate the inboard shift pressure control valve. This controls Drive and Reverse fluid pressure to manage second clutch (B2), second coast clutch (B1) or direct clutch (C2) application.
The constant oscillation of the valve within the sleeve creates wear, allowing crucial SLS pressure to exhaust. This can result in shift concerns, high line pressure, and burnt clutches. Installing Sonnax shift pressure control plunger valve kit 59947-75K restores hydraulic integrity to this circuit with upgraded materials to prevent future deterioration.
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.
Prior to removal, the inboard shift pressure control valve should be checked for excess wear by vacuum testing (Figure 1). If testing at the port indicated fails to hold the recommended minimum in-Hg, replace with Sonnax shift pressure control valve kit [59947-38K].
If shift pressure control valve passes testing, proceed to test shift pressure control plunger valve and sleeve (Figure 2). If testing at the port indicated fails to hold the recommended minimum in-Hg, install Sonnax shift pressure control plunger valve kit 59947-75K.