Automatic Transmission/Transaxle Control Unit (ATCU)

ATCU receives input signals from the ignition coil (RPM signal), idle switch (on-off signal), throttle sensor (variable signal) and full throttle switch (on-off signal). Based on these values, the ATCU calculates optimum timing and duration to energize shift solenoids, overrun clutch solenoid and lock-up solenoid. ATCU also indicates when overdrive is engaged (if equipped) by illuminating the OD indicator light.