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