Differential Clutch Pump Actuator Check Valve
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
The differential clutch pump actuator check valve controls the oil flow to the gerotor pumps. Without fluid pressure the pistons cannot apply the clutch packs for rear wheel engagement. The actuator check valve will open upon engine start-up and remain open unless commanded closed by the powertrain control module. The actuator check valve also monitors the sump oil for an overtemperature condition. If differential oil temperature exceeds 110°C (230°F), the valve will close and block oil flow to the gerotor pumps.