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 coastdown.

Closed Throttle Coastdown: 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. This condition may also be 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 causes 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 occurs 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 two opposing clutches (usually one oncoming and one offgoing) are applied at the same time. Gives 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. This noise 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

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

ECT: Engine Coolant Temperature

EMI: Electromagnetic Interference

IGN: Ignition

MIL: Malfunction Indicator Lamp

NC: Normally Closed

NO: Normally Open

OBD: On Board Diagnostic

PCCS: PROM Calibration Configurator System

PNP: Park/Neutral Position

PWM: Pulse Width Modulation

PTO: Power Takeoff

RPM: Revolutions Per Minute

TCC: Torque Converter Clutch

TCM: Transmission Control Module

TFT: Transmission Fluid Temperature

TP: Throttle Position

TPS: Throttle Position Sensor

VCM: Vehicle Control Module

WOT: Wide-Open Throttle

2WD: Two-Wheel Drive

4WD: Four-Wheel Drive