Overhaul - Aw-4: Description

Transmission is a 4-speed overdrive electronically controlled automatic transmission. Transmission consists of lock-up torque converter, oil pump, 3 planetary gear sets, clutch and brake units, accumulator pistons, valve body and 3 valve body solenoids.

Valve body with electronic solenoids and a Transmission Control Unit (TCU) are used for controlling transmission operation. Valve body solenoids are controlled by the TCU. The No. 1 and No. 2 valve body solenoids are used for controlling the transmission shifts. The No. 3 valve body solenoid is used for torque converter lock-up.

The TCU determines shift points and torque converter lock-up timing based on input signals received from throttle position sensor, neutral safety switch, speed sensor and brake pedal switch. The TCU contains a electronic self-diagnostic system used for determining a transmission failure. The electronic self-diagnostic system stores a fault code if certain transmission failures exist.