Automatic Transmission - Overhaul - 4R44E & 4R55E Automatic Transmission: Description

The 4R44E/4R55E is a 4-speed automatic overdrive transmission with lock-up type torque converter and electronic controls. The 4R44E is used with 2.3L and 3.0L engine applications. The 4R55E is used with 4.0L engine applications. Transmission consists of torque converter, 3 compound planetary gearsets, 3 multiple disc clutch packs, 3 bands and 2 one-way clutches.

Shift control solenoids control gear selection and are operated by the EEC-IV (1995) or EEC-V (1996) microprocessor. For additional information on the EEC-IV or EEC-V system, refer to appropriate TESTS W/CODES article in ENGINE PERFORMANCE section.

Input signals from sensors are sent to the Powertrain Control Module (PCM). The PCM can determine when the time and conditions are right for a shift or converter clutch application. The PCM can also determine line pressure needed to optimize shift feel.

Six electronic solenoids accomplish these functions as follows:

• 3 On/Off solenoids for shifting.
• One Pulse-Width Modulator (PWM) solenoid for Torque Converter Clutch (TCC) control.
• One Electronic Pressure Control (EPC) solenoid for line pressure control.
• One 3-2 timing/coast clutch solenoid to control release of coast clutch, coordinated release of the direct clutch, and apply of the low and intermediate band.

PCM has built-in self-diagnosis, fail-safe code and warning code display for the main input sensors and solenoid valves.