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 off-going, 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