Automatic Transaxle - 4T65-E - Introduction (2 of 2): Overview Chevrolet Uplander I

Automatic Transmission Schematic Icons

Automatic Transmission Schematic Icons Icon Icon Definition NOTE: The OBD II symbol is used on the circuit diagrams in order to alert the technician that the circuit is essential for proper OBD II emission control circuit operation. Any circuit which fails and causes the malfunction indicator lamp (MIL) to turn ON or causes emissions-related component damage, is identified as an OBD II circuit. IMPORTANT: Twisted-pair wires provide an effective "shield" that helps protect sensitive electronic components from electrical interference. If the wires were covered with shielding, install new shielding. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 9 turns per 31 cm (12 in) as measured anywhere along the length of the wires The outside diameter of the twisted wires must not exceed 6.0 mm

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Transmission General Description

The 4T65-E is a fully automatic front wheel drive electronically controlled transmission. The 4T65-E provides four forward ranges including overdrive. The PCM controls shift points by means of two shift solenoids. A vane-type oil pump supplies the oil pressure. The PCM regulates oil pressure by means of a pressure control solenoid valve.

All vehicles equipped with a 4T65-E transmission have an electronically controlled capacity clutch (ECCC) system. In the ECCC system, the pressure plate does not fully lock to the torque converter cover. It is instead, precisely controlled to maintain a small amount of slippage between the engine and the turbine, reducing driveline torsional disturbances.

You can operate the transmission in any one of the following seven modes

1. P - Park position prevents the vehicle from rolling either forward or backward. For safety reasons, use the parking brake in addition to the park position.
2. R - Reverse allows the vehicle to be operated in a rearward direction.
3. N - Neutral allows the engine to be started and operated while driving the vehicle. If necessary, you may select this position in order to restart the engine with the vehicle moving.
4. D - Overdrive is used for all normal driving conditions. Overdrive provides four gear ratios plus a converter clutch operation. Depress the accelerator in order to downshift for safe passing.
5. 3 - Drive position is used for city traffic and hilly terrain. Drive provides three gear ranges and drive range prevents the transmission from operating in fourth gear. Depress the accelerator in order to downshift.
6. 2 - Manual Second provides two gear ratios under most operating conditions. Manual Second provides acceleration and engine braking. Select this range at any vehicle speed, but the transmission will not downshift into Second gear until the vehicle speed drops below approximately 100 km/h (62 mph)
7. 1 - Manual Lo provides maximum engine braking. You may also select this range at any vehicle speed, but the transmission will not downshift into First gear until the vehicle speed drops below approximately 60 km/h (37 mph).

Transmission Component and System Description

The mechanical components of this unit are as follows

1. A torque converter with an electronically controlled capacity clutch (ECCC) This transmission is equipped with an ECCC. The pressure plate does not fully lock to the torque converter cover. Instead, the pressure plate maintains a small amount of slippage, about 20 RPM, in SECOND, THIRD and FOURTH gears, depending on the vehicle application. ECCC was developed to reduce the possibility of noise, vibration or chuggle caused by torque converter clutch (TCC) apply. Typical apply speeds are 49-52 km/h (30-32 mph) in THIRD gear and 65-73 km/h (40-45 mph) in FOURTH gear. Full lockup is available at highway speeds on some applications.
2. A drive link assembly
3. 4 multiple disk clutch assemblies: Input, Second, Third and Fourth
4. 3 friction bands: Forward band, 2/1 band and Reverse band
5. 2 planetary gear sets: Input and Reaction
6. 3 one-way clutches: a roller clutch (1-2 support) and 2 sprag clutches (Third and Input)
7. A final drive and differential assembly
8. A control valve assembly
9. A vane type oil pump

The electrical components of this unit are as follows

1. 2 shift solenoid valves
2. A torque converter clutch pulse width modulation (TCC PWM) solenoid valve
3. A pressure control (PC) solenoid valve
4. An automatic transmission fluid temperature (TFT) sensor
5. 2 speed sensors: input shaft and vehicle speed sensors
6. An automatic transmission fluid pressure (TFP) manual valve position switch
7. Either an internal mode switch (IMS) or an externally-mounted transmission range (TR) switch.
8. An automatic transmission (A/T) wiring harness assembly

For more information, refer to Electronic Component Description .