Minimum Throttle

The least amount of throttle opening required for an upshift

Light Throttle

Approximately 1/4 of accelerator pedal travel (25% Throttle Position).

Medium throttle

Approximately 1/2 of accelerator pedal travel (50%Throttle Position).

Heavy throttle

Approximately 3/4 of accelerator pedal travel (75% Throttle Position).

Wide Open Throttle (WOT)

Full travel of the accelerator pedal (100% Throttle Position).

Full Throttle Detent Downshift

A quick apply of the accelerator pedal to its full travel, forcing a downshift.

Zero throttle Coast down

A full release of the accelerator pedal while the car is in motion and in drive range.

Engine Braking

A condition where the engine is used to slow the car by manually downshifting during a zero throttle coast down.

Planetary Gear Noise

A whine related to car speed most noticeable in first gear of reverse. Become less noticeable after an upshift.

Pump Noise

A high pitch whine that increases with engine RPM

Accumulator

A component of the transmission that absorbs hydraulic pressure during the apply of a clutch or band. Accumulators are designed to control the quality of a shift from one gear range to another.

Adaptive Learning

Programming within the PCM that automatically adjusts hydraulic pressures in order to compensate for changes in the transmission (i.e. component wear).

Applied

An 'Applied component' is one that is holding another component to which it is splined or assembled to. Also referred to as "engaged"

Apply Components

Hydraulically operated clutches, servo's, bands and mechanical one-way roller or sprag clutches that drive or hold members of a planetary gear set.

Apply Plate

A steel clutch plate in a clutch pack, located next to the (apply) piston.

Backing Plate

A steel plate in a clutch pack that is usually the last plate in that clutch assembly (furthest from the clutch piston).

Band

An apply component that consists of a flexible strip of steel and friction material that wraps around a drum. When applied, it tightens around the drum and prevents the drum from rotating.

Brake Switch

An electrical device that provides signals to the powertrain control module (PCM), based on the position of the brake pedal. The PCM uses this information to apply or release the torque converter clutch (TCC).

Centrifugal Force

A force that is imparted on an object (due to rotation) that increases as that object moves further away from a center-point of rotation.

Check ball

A spherical, hydraulically controlled component (usually of steel) that either seals or opens fluid circuits. it is also referred to as a check valve.

Clutch Pack

An assembly of components generally consisting of clutch plates, an apply plate and a backing plate.

Clutch Plate

A hydraulically activated component that has two basic designs: (1) all steel, or (2) a steel core with friction material bonded to one or two sides of the plate.

Control Valve Body

A machined metal casting that contains valve trains and other hydraulically controlled components that shift the transmission

Coupling Speed

the speed at which a vehicle is traveling and no longer requires torque multiplication through the torque converter. At this point, the stator 'free wheels' to allow fluid leaving the turbine to flow directly to the pump. (Also see Torque Converter).

De-energize(d)

To interrupt the electrical current that flows to an electronically controlled device, making it electrically inoperable.

Direct Drive

A condition in a gears set where the input speed and input torque equals the output speed and output torque. The gear ratio through the gear set is 1:1

Downshift

A change in a gear ratio where both input speed and torque increases.

Duty Cycle

In reference to an electronically controlled solenoid, it is the amount of time (expressed as a percentage) that current flows through the solenoid coil.

Energize(d)

To supply a current to an electronically controlled device, enabling it to perform its designed function.

Engine Compression Braking

A condition where compression from the engine is used with the transmission to decrease vehicle speed.

Exhaust

The release of fluid pressure from a hydraulic circuit. (the words 'exhausts' and 'exhausting' are also used and have the same intended meaning.)

Fail-safe Mode

A condition whereby a component (i.e. engine or transmission) will partially function even if its electrical circuit is disabled.

Fluid

In this "Section of the Service Manual, 'fluid' refers primarily to Automatic Transmission fluid (or ATF) and, for the Hydra-matic 4L65E transmission, the only recommended fluid is Dexron® III

Fluid Pressure

A pressure that is consistent throughout a given fluid circuit.

Force

A measurable effort that is exerted on an object (component).

Freewheeling

A condition where power is lost through a driving or holding device (i.e. roller or sprag clutches).

Friction Material

A heat and wear resistant fibrous material, bonded to clutch plates and bands.

Gear

A round, toothed device that is used for transmitting torque through other components.

Gear Range

A specific speed to torque ratio at which the transmission is operating (i.e. 1st gear, 2nd gear etc.).

Gear Ratio

Revolutions of an input gear as compared to the revolutions of an output gear. It can also be expressed as the number of teeth on a gear as compared to the number of teeth on a gear that it is in mesh with.

Hydraulic Circuit

A fluid passage which often includes the mechanical components in that circuit designed to perform a specific function.

Input

A starting point for torque, revolutions or energy into another component of the transmission.

Internal Gear

The outermost member of a gear set that has gear teeth in constant mesh with the planetary pinion gears of the gear set.

Land (Valve Land)

The larger diameters of a spool valve that contact the valve bore or bushing.

Line Pressure

The main fluid pressure in a hydraulic system created by the pump and pressure regulator valve.

Manual Valve

A spool valve that distributes fluid to various hydraulic circuits and is mechanically linked to the gear selector lever.

Orifice

A restricting device (usually a hole in the spacer plate) for controlling pressure build up into another circuit.

Overdrive

An operating condition in the gear set allowing output speed to be higher than input speed and output torque to be lower than input torque

Overrunning

The function of a one-way mechanical clutch that allows the clutch to freewheel during certain operating conditions of the transmission.

Pedal Position

The percentage angle of the accelerator pedal as displayed by Tech 2.

Pinion Gears

Pinion gears (housed in a carrier) that are in constant mesh with a circumferential internal gear and centralized sun gear.

Planetary Gear Set

An assembly of gears that consists of an internal gear, planet pinion gears with a carrier, and a sun gear.

Powertrain Control Module (PCM)

An electronic device that manages the vehicle's engine and automatic transmission functions.

Pressure

A measurable force that is exerted on an area and expressed as kilopascals (kPa).

Pulse Width Modulated (PWM)

An electronic signal that continuously cycles the On and Off time of a device (such as a solenoid) while varying the amount of On time.

Race (Inner or Outer)

A highly polished steel surface that contacts bearings or sprag or roller elements.

Reduction (Gear Reduction)

An operating condition in the gear set allowing output speed to be lower than input speed and output torque to be higher than input torque.

Residual Fluid Pressure

Excess pressure contained within an area after the supply pressure has been terminated.

Roller Clutch

A mechanical clutch (holding device ) consisting of roller bearing assembled between inner and outer races.

Servo

A spring loaded device consisting of a piston in a bore that is operated (stroked) by hydraulic pressure to apply or release a band.

Spool Valve

A round hydraulic control valve often containing a variety of land and valley diameters.

Sprag Clutch

A mechanical clutch (holding device consisting of "figure eight" like elements assembled between inner and outer races.

Staking

The effect of deforming, peening over or riveting a shaft to provide a solid mounting.

Throttle Position

The travel of the throttle plate that is expressed in percentages and measured by Tech 2.

Torque

A measurable twisting force expressed in terms of Newton Meters (N·m).

Torque Converter

A component of an automatic transmission, (attached to the engine flex plate ) that transfers torque from the engine to the transmission through a fluid coupling.

Torx® Plus Bit

A special tool used for the removal of the bell housing. Precision tip fit means that cam out of the bolt head is virtually eliminated.

Important: Torx® Plus bits are different from normal Torx® Bits

Variable Capacity Pump

The device that provides fluid for operating the hydraulic circuits in the transmission. The amount of fluid supplied varies depending on vehicle operating conditions.

2WD

Two Wheel Drive

AC

Alternating Current

A/C

Air Conditioning

AFL

Actuator Feed Limit

AWD

All Wheel Drive

DC

Direct Current

D.C.

Duty Cycle

ECM

Engine Control Module

ECT Sensor

Engine Coolant Temperature Sensor

ETC

Electronic Throttle Control

N.C.

Normally Closed

N.O.

Normally Open

PCM

Powertrain Control Module

PCS

Pressure Control Solenoid (or Force Motor)

PIM

Powertrain Interface Module

PWM

Pulse Width Modulated

RWD

Rear Wheel Drive

TCC

Torque Converter Clutch

TFP Switch

Transmission Fluid Pressure Manual Valve Position Switch

TFT

Transmission Fluid Temperature Sensor

TP Sensor

Throttle Sensor

VS Sensor

Vehicle Speed Sensor