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