EGR Signal
The SCAN tool monitors only the Electronic Control Module (ECM) drive command to the Exhaust Gas Recirculation (EGR) solenoid. On models with Pulse Width Modulated EGR, reading is duty cycle of ECM signal from 0-100 percent. On models with EGR solenoid, ``on'' or ``off'' status of solenoid is indicated. Normal reading with engine running at idle should be 0 or off.