General System Description

The 4L60E is an electronically controlled version of the 4L6O transmission. A Powertrain Control Module (PCM) manages engine and transmission functions as a single system. The PCM retards engine spark for an instant during each gear shift which reduces engine torque as the gear is engaged. After the shift is completed, spark is advanced and torque is brought to normal operating levels. Shifting is accomplished by sensor-driven servos located within the transmission valve body.