US Patent 7185628 Continuous engine reverse rotation detection system

A reverse rotation detection system for an engine with at least one camshaft and a crankshaft includes a camshaft position sensor that generates a camshaft position signal based on a rotation of the camshaft. A second sensor input device generates a crankshaft position signal based on a rotation of the crankshaft. A control module detects a reverse rotation condition of the engine from the camshaft position signal and the crankshaft position signal, wherein the control module compares the camshaft position signal to the crankshaft position signal to determine an engine position. Based on the engine position the control module compares the camshaft position signal to an expected signal to determine a reverse rotation condition.