Throttle Positions

Engine Braking: A condition where the engine is used to slow the vehicle by manually downshifting during a zero throttle coastdown.

Full Throttle Detent Downshift: A quick apply of the accelerator pedal to its full travel, forcing a downshift.

Heavy Throttle: Approximately 3/4 of accelerator pedal travel (75 percent throttle position).

Light Throttle: Approximately 1/4 of accelerator pedal travel (25 percent throttle position).

Medium Throttle: Approximately 1/2 of accelerator pedal travel (50 percent throttle position).

Minimum Throttle: The least amount of throttle opening required for an upshift.

Wide Open Throttle (WOT): Full travel of the accelerator pedal (100 percent throttle position).

Zero Throttle Coastdown: A full release of the accelerator pedal while the vehicle is in motion and in drive range.

Shift Conditions

Bump: A sudden and forceful apply of a clutch or a band.

Chuggle: A bucking or jerking. This condition may be most noticeable when the converter clutch is engaged. It is similar to the feel of towing a trailer.

Delayed: A condition where a shift is expected but does not occur for a period of time. This could be described as a clutch or band engagement that does not occur as quickly as expected during a part throttle or wide open throttle apply of the accelerator, or during manual downshifting to a lower range. This term is also defined as LATE or EXTENDED.

Double Bump (Double Feel): Two sudden and forceful applies of a clutch or a band.

Early: A condition where the shift occurs before the car has reached proper speed. This condition tends to labor the engine after the upshift.

End Bump: A firmer feel at the end of a shift than at the start of the shift. This is also defined as END FEEL or SLIP BUMP.

Firm: A noticeably quick apply of a clutch or band that is considered normal with a medium to heavy throttle. This apply should not be confused with HARSH or ROUGH.

Flare: A quick increase in engine RPM along with a momentary loss of torque. This most generally occurs during a shift. This condition is also defined as SLIPPING.

Harsh (Rough): A more noticeable apply of a clutch or band than FIRM. This condition is considered undesirable at any throttle position.

Hunting: A repeating quick series of upshifts and downshifts that causes a noticeable change in engine RPM, such as a 4-3-4 shift pattern. This condition is also defined as BUSYNESS.

Initial Feel: A distinctly firmer feel at the start of a shift than at the finish of the shift.

Late: A shift that occurs when the engine's RPM is higher than normal for a given amount of throttle.

Shudder: A repeating jerking condition similar to CHUGGLE but more severe and rapid. This condition may be most noticeable during certain ranges of car speed.

Slipping: A noticeable increase in engine RPM without a car speed increase. A slip usually occurs during or after initial clutch or band apply.

Soft: A slow, almost unnoticeable clutch or band apply with very little shift feel.

Surge: A repeating engine related condition of acceleration and deceleration that is less intense than CHUGGLE.

Tie-Up: A condition where two opposing clutch and/or bands are attempting to apply at the same time causing the engine to labor with a noticeable loss of engine RPM.

Noise Conditions

Planetary Gear Noise: a whine related to car speed. This noise is most noticeable in FIRST gear, SECOND gear, FOURTH gear, or REVERSE. The condition becomes less noticeable after an upshift.

Pump Noise: a high pitched whine that increases with engine RPM and may be affected by modulated line pressure boost.

Transmission Abbreviations

PCM: powertrain control module

VCM: vehicle control module

TCC: torque converter clutch

TP sensor: throttle position sensor

ECT sensor: engine coolant temperature sensor

VSS sensor: vehicle speed sensor

RWD: rear wheel drive

2WD: two-wheel drive

4WD: four-wheel drive

TFT: automatic transmission fluid temperature

TFP manual valve position switch assembly: automatic transmission fluid pressure manual valve position switch assembly

A/T ISS sensor: automatic transmission input (shaft) speed sensor

OSS sensor: automatic transmission output (shaft) speed sensor

A/T wiring harness assembly: automatic transmission wiring harness assembly

PC solenoid valve: pressure control solenoid valve

1-2 SS valve: 1-2 shift solenoid valve

2-3 SS valve: 2-3 shift solenoid valve

TCC PWM solenoid valve: torque converter clutch pulse width modulation solenoid valve