Third and Fourth Gear Switch

The third and fourth gear switches are located in the transmission. They are used to tell the Electronic Control Module (ECM) when the transmission is in third or fourth gear. The ECM uses this information to vary the conditions under which the Viscous Converter Clutch (VCC) applies or releases. The VCC can apply in second gear under engine overheat conditions. Second gear application will reduce transmission fluid temperature and allow the radiator to provide improved cooling to the engine.