Circuit/System Description
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The OSS system is a pulse generator consisting of a speed sensor assembly, located in the case extension, and a toothed vehicle speed sensor (VSS) reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle drives forward, the VSS reluctor wheel rotates. This rotation produces a variable AC signal in the pick-up coil that is proportional to vehicle speed. The transmission control module (TCM) uses this signal in order to calculate vehicle speed, shift timing, and gear ratios.