Transmission General Description

The Hydra-Matic 4L30-E is a fully automatic, four speed, rear wheel drive transmission. It consists primarily of a four-element torque converter, two planetary gear sets, various clutches, an oil pump, and a control valve body.
The four-element torque converter contains a pump, a turbine, a pressure plate splined to the turbine, and a stator assembly. The torque converter acts as a fluid coupling to smoothly transmit power from the engine to the transmission. It also hydraulically provides additional torque multiplication when required. The pressure plate, when applied, provides a mechanical "direct drive" coupling of the engine to the transmission.
The two planetary gear sets provide the four forward gear ratios and reverse. Changing of the gear ratios is fully automatic and is accomplished through the use of various electronic powertrain sensors that provide input signals to the Transmission Control Module (TCM). The TCM interprets these signals to send current to the various solenoids inside the transmission.
By using electronics, the TCM controls shift points, shift feel and torque converter clutch apply and release, to provide proper gear ranges for maximum fuel economy and vehicle performance.
Five multiple-disc clutches, one roller clutch, a sprag clutch, and a brake band provide the friction elements required to obtain the various ratios with planetary gear sets.
A hydraulic system (the control valve body), pressurized by a gear type pump provides the working pressure needed to operate the friction elements and automatic controls.
Several electronic solenoids and sensors in the powertrain work in conjunction with the vehicle's Transmission Control Module (TCM), to control various shift points, shift feel and converter clutch apply and release.
You can operate the transmission in any one of the following seven modes:
- P - PARK position prevents the vehicle from rolling either forward or backward on vehicles less than 15,000 G.V.W. For safety reasons, use the parking brake in addition to the park position.
- R - REVERSE allows the vehicle to be operated in a rearward direction.
- 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.
- D - DRIVE is used for all normal driving conditions. Drive provides four gear ratios plus a converter clutch operation. Depress the acceleration order to downshift for safe passing.
- 3 - Manual THIRD position is used for city traffic, and hilly terrain. Manual THIRD provides three gear ranges. Depress the accelerator in order to downshift.
- 2 - Manual SECOND provides acceleration and engine braking or greater traction from a stop. When you choose manual SECOND, the vehicle will start out in first gear and upshift to second gear. You may select this gear at a vehicle speed of up to 22 km/h (35 mph).
- 1 - Manual LOW provides maximum engine braking. You may select this gear at a vehicle speed of up to 13 km/h (20 mph).