Chevrolet Silverado / GMC Sierra. Service manual — part 996

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado