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

Drive Link Noise: A whine or growl that increases or fades with engine RPM. This noise is most noticeable under a light throttle acceleration, or in Park or Neutral with the car stationary.

Final Drive Noise: A hum related to car speed. This noise is most noticeable under a light throttle acceleration or zero throttle coastdown.

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

A/C: Air Conditioning

A/T ISS Sensor: Automatic Transmission Input (Shaft) Speed Sensor

AC: Alternating Current

CKT: Circuit

DC: Direct Current

DLC: Diagnostic Link Connector

DTC: Diagnostic Trouble Code

ECT Sensor: Engine Coolant Temperature Sensor

MAP: Manifold Absolute Pressure

MIL: Malfunction Indicator Lamp

NC: Normally Closed

NO: Normally Open

OBD: On Board Diagnostic

PCM: Powertrain Control Module

PC Sol. Valve: Pressure Control Solenoid Valve

PM: Permanent Magnet

PWM: Pulse Width Modulation

RPM: Revolutions Per Minute

TCC Sol. Valve: Torque Converter Clutch Solenoid Valve

TFP Val. Position Sw.: Automatic Transmission Fluid Pressure Manual Valve Position Switch

TFT: Automatic Transmission Fluid Temperature

TP Sensor: Throttle Position Sensor

VSS Assy.: Vehicle Speed Sensor Assembly

WOT: Wide Open throttle