Definitions and Abbreviations

Definitions and Abbreviations
Throttle Positions

Engine Braking
A condition where the engine friction is used to slow the vehicle by manually downshifting during a zero throttle coastdown.

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

Heavy Throttle
Approximately 3/4 of accelerator pedal travel (75 percent throttle position).

Light Throttle
Approximately 1/4 of accelerator pedal travel (25 percent throttle position).

Medium Throttle
Approximately 1/2 of accelerator pedal travel (50 percent throttle position).

Minimum Throttle
The least amount of throttle opening required for an upshift.

Wide Open Throttle (WOT)
Full travel of the accelerator pedal (100 percent throttle position).

Zero Throttle Coastdown
A full release of the accelerator pedal while the vehicle is in motion and in drive range.

Shift Condition Definitions

Bump
A sudden and forceful apply of a clutch or a band.

Chuggle
A bucking or jerking. This condition may be most noticeable when the converter clutch is engaged. It is similar to the feel of towing a trailer.

Delayed
A condition where a shift is expected but does not occur for a period of time. This could be described as a clutch or band engagement that does not occur as quickly as expected during a part throttle or wide open throttle apply of the accelerator, or during manual downshifting to a lower range. This term is also defined as LATE or EXTENDED.

Double Bump (Double Feel)
Two sudden and forceful applies of a clutch or a band.

Early
A condition where the shift occurs before the car has reached proper speed. This condition tends to labor the engine after the upshift.

End Bump
A firmer feel at the end of a shift than at the start of the shift. This is also defined as END FEEL or SLIP BUMP.

Firm

A noticeably quick apply of a clutch or band that is considered normal with a medium to heavy throttle. This apply should not be confused with HARSH or ROUGH.

Flare
A quick increase in engine RPM along with a momentary loss of torque. This most generally occurs during a shift. This condition is also defined as SLIPPING.

Harsh (Rough)
A more noticeable apply of a clutch or band than FIRM. This condition is considered undesirable at any throttle position.

Hunting
A repeating quick series of upshifts and downshifts that causes a noticeable change in engine RPM, such as a 4-3-4 shift pattern. This condition is also defined as BUSYNESS.

Initial Feel
A distinctly firmer feel at the start of a shift than at the finish of the shift.

Late
A shift that occurs when the engine RPM is higher than normal for a given amount of throttle.

Shudder
A repeating jerking condition similar to CHUGGLE but more severe and rapid. This condition may be most noticeable during certain ranges of vehicle speed.

Slipping
A noticeable increase in engine RPM without a vehicle speed increase. A slip usually occurs during or after initial clutch or band apply.

Soft
A slow, almost unnoticeable clutch or band apply with very little shift feel.

Surge
A repeating engine related condition of acceleration and deceleration that is less intense than CHUGGLE.

Tie-Up
A condition where two opposing clutch and/or bands are attempting to apply at the same time causing the engine to labor with a noticeable loss of engine RPM.

Noise Conditions

Drive Link Noise
A whine or growl that increases or fades with vehicle speed, and is most noticeable under a light throttle acceleration. It may also be noticeable in PARK or NEUTRAL operating ranges with the vehicle stationary.

Final Drive Noise
A hum related to vehicle speed which is most noticeable under a light throttle acceleration.

Planetary Gear Noise
A whine related to vehicle speed, which is most noticeable in FIRST gear, SECOND gear, FOURTH gear or REVERSE. The condition may become less noticeable, or go away, after an upshift.

Pump Noise
A high pitched whine that increases in intensity with engine RPM. This condition may also be noticeable in all operating ranges with the vehicle stationary or moving.

Torque Converter Noise
A whine usually Notice: d when a vehicle is stopped, and the transmission is in DRIVE or REVERSE. The noise will increase with engine RPM.

Transmission Abbreviations

A/C
Air Conditioning

AC
Alternating Current

AT
Automatic Transmission

CCDIC
Climate Control Driver Information Center

DC
Direct Current

DIC
Driver Information Center

DLC
Diagnostic Link Connector

DMM
Digital Multimeter

DTC
Diagnostic Trouble Code

ECT
Engine Coolant Temperature

EMI
Electromagnetic Interference

IAT
Intake Air Temperature

IGN
Ignition

MAP
Manifold Absolute Pressure

MIL
Malfunction Indicator Lamp

NC
Normally Closed

NO
Normally Open

OBD
On Board Diagnostic

OSS
Output (Shaft) Speed Sensor

PC
Pressure Control

PCM
Powertrain Control Module

PWM
Pulse Width Modulation

RPM
Revolutions Per Minute

SS
Shift Solenoid

TAP
Transmission Adaptive Pressure

TCC
Torque Converter Clutch

TFP
Transmission Fluid Pressure

TFT
Transmission Fluid Temperature

TP
Throttle Position

TV
Throttle Valve

VSS
Vehicle Speed Sensor

WOT
Wide Open Throttle

4WD
Four-Wheel Drive