Definitions and Abbreviations

Definitions and Abbreviations

Throttle Position Definitions

Heavy Throttle

-
Approximately 75% of accelerator pedal travel

Light Throttle

-
Approximately 25% of accelerator pedal travel

Medium Throttle

-
Approximately 50% of accelerator pedal travel

Wide-Open Throttle (WOT)

-
Full travel of the accelerator pedal, 100% throttle

Closed Throttle

-
Foot is off the accelerator pedal or pedal is not depressed, 0% throttle

Throttle-Related Shift Condition Definitions

Closed Throttle Manual Downshift

-
A condition where the engine is used to slow the vehicle by manually downshifting during a closed throttle coast down

Closed Throttle Coast Down

-
A full release of the accelerator pedal while the transmission remains in DRIVE range, allowing the transmission to downshift as vehicle speed reduces

WOT Detent Downshift

-
Quick apply of the accelerator pedal to its full travel, forcing a downshift

WOT Upshifts/Downshifts

-
Accelerator pedal is fully depressed and transmission shifts sequentially through ranges as dictated by load and grade

Shift Condition Definitions

Bump

-
A sudden and forceful apply of a clutch

Delayed

-
A shift was expected but did not occur for several seconds, as during a manual downshift or WOT detent downshift - may also be defined as Late or Extended

Double Bump

-
Two bumps felt during a clutch apply

Early

-
Shift occurs at lower speed than expected, often accompanied by engine laboring after an upshift

End Bump

-
A firmer feel at the end of a shift than at the start of a shift

Firm

-
A noticeably quick apply of a clutch at medium or heavy throttle conditions - DO NOT confuse with Harsh or Rough

Flare

-
A quick increase in engine speed along with a momentary loss of torque during a shift transition - also defined as Slipping

Harsh - Rough

-
More noticeable clutch apply than Firm - considered unacceptable at any throttle position

Hunting

-
A repeating quick series of upshifts and downshifts that cause a noticeable change in engine speed, such as 4-3-4, etc. - sometimes defined as Cycling

Initial Feel

-
A distinctly firmer feel at the start of a shift than at the finish of a shift

Late

-
A shift that occurs at a higher speed than normal for a given throttle position

Shudder

-
Multiple, rapid jerks usually associated with an oncoming clutch

Slipping

-
A noticeable increase in engine speed without an increase in vehicle speed - usually occurring just after the initial application of a clutch

Soft

-
A slow, almost unnoticeable, clutch apply

Surge

-
A repeating engine-related condition of acceleration and deceleration that is less intense than Shudder

Tie-up

-
A condition where 2 opposing clutches, usually 1 oncoming and 1 offgoing, are applied at the same time - giving a braking sensation and/or loss of engine speed

Noise Conditions

Planetary Gear Noise

-
A whine related to engine speed and noticeable in a particular transmission range - may be less noticeable or disappear following a transmission upshift

Pump Noise

-
A high pitched whine that increases in intensity with increasing engine speed - may occur in any transmission range and with the vehicle moving or stationary

Torque Converter Noise

-
A whine usually noticed when the vehicle is stopped and the transmission is in D, DRIVE, or R, REVERSE

Thermostatic Fan Noise

-
A normal noise that occurs while climbing a grade under load, caused by the engaging/disengaging of the engine cooling fan thermostatic clutch

Transmission Abbreviations

AC

-
Alternating Current

DC

-
Direct Current

DLC

-
Diagnostic Link Connector

DMM

-
Digital Multimeter

DTC

-
Diagnostic Trouble Code

ECM

-
Engine Control Module

ECT

-
Engine Coolant Temperature

EMI

-
Electromagnetic Interference

IGN

-
Ignition

IMS

-
Internal Mode Switch

MIL

-
Malfunction Indicator Lamp

NC

-
Normally Closed

NO

-
Normally Open

OBD

-
On Board Diagnostic

PCS

-
Pressure Control Solenoid

PS

-
Pressure Switch

PTO

-
Power Take-Off

RPM

-
Revolutions Per Minute

SS

-
Shift Solenoid

TCC

-
Torque Converter Clutch

TCM

-
Transmission Control Module

TFT

-
Transmission Fluid Temperature

TP

-
Throttle Position

TPS

-
Throttle Position Sensor

VBS

-
Variable Bleed Solenoid

WOT

-
Wide-Open Throttle

2WD

-
Two-Wheel Drive

4WD

-
Four-Wheel Drive