Chevrolet Silverado / GMC Sierra. Manual

Fig. 536: Bar Code Label Contents
Courtesy of GENERAL MOTORS CORP.

Plant and Shift Build Chart

Case/Pan Frame Rail Area

Callout

Component Name

8 = 2008

Model

Hydra-Matic 4L60-E

Transmission Asm. as Shipped Number

8 = Model Year

Julian Date or Day of the Year

Letter After Julian Date Identifies the Plant Shift Build, See Shift Build
Chart

Bar Code

Serial Number

Broadcast Code

Transmission ID

Build Location Y = Toledo, OH, 4 = Ramos Arizpe, Mexico

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

TRANSMISSION COMPONENT AND SYSTEM DESCRIPTION

The mechanical components of the 4L60-E are as follows:

A torque converter with an electronically controlled capacity clutch (ECCC)

This transmission is equipped with an ECCC. The pressure plate does not fully lock to the
torque converter cover. Instead, the pressure plate maintains a small amount of slippage,
about 20 RPM, in SECOND, THIRD, and FOURTH gears, depending on the vehicle
application. ECCC was developed to reduce the possibility of noise, vibration, or chuggle
caused by TCC apply. Typical apply speeds are 49-52 km/h (30-32 mph) in THIRD gear
and 65-73 km/h (40-45 mph) in FOURTH gear. Full lockup is available at highway speeds
on some applications.

Torque converter assembly

Servo assembly and 2-4 band assembly

Reverse input clutch and housing

Overrun clutch

Forward clutch

3-4 clutch

Forward sprag clutch assembly

Lo and reverse roller clutch assembly

Lo and reverse clutch assembly

Two planetary gear sets: Input and Reaction

Oil pump assembly

Control valve body assembly

The electrical components of the 4L60-E are as follows:

Plant

Build Line

1st Shift

2nd Shift

3rd Shift

Toledo, OH

ML1

ML2

Not Used

ML3

Not Used

ML4

ML5

Ramos Arizpe,

Mexico

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

1-2 and 2-3 shift solenoid valves

3-2 shift solenoid valve assembly

Transmission pressure control (PC) solenoid

Torque converter clutch (TCC) solenoid valve

TCC pulse width modulation (PWM) solenoid valve

Automatic transmission fluid pressure (TFP) manual valve position switch

Automatic transmission fluid temperature (TFT) sensor

Vehicle speed sensor assembly

For more information, refer to Electronic Component Description (TCM).

TRANSMISSION ADAPTIVE FUNCTIONS (TCM)

The 4L60-E transmission utilizes a line pressure control system during upshifts to compensate for
the normal wear of transmission components. By adjusting the line pressure, the transmission
control module (TCM) can maintain acceptable transmission shift times. This process is known as
"adaptive learning" or "shift adapts" and is similar to the closed loop fuel control system used for
the engine.

In order for the TCM to perform a "shift adapt," it must first identify if an upshift is acceptable to
analyze. For example, upshifts that occur during cycling of the A/C compressor or under extreme
throttle changes could cause the TCM to incorrectly adjust line pressure. When an upshift is
initiated, a number of contingencies, such as throttle position, transmission temperature, and
vehicle speed, are checked in order to determine if the actual shift time is valid to compare to a
calibrated desired shift time. If all the contingencies are met during the entire shift, then the shift
is considered valid and the adapt function may be utilized if necessary.

Once an adaptable shift is identified, the TCM compares the actual shift time to the desired shift
time and calculates the difference between them. This difference is known as the shift error. The
actual shift time is determined from the time that the TCM commands the shift to the start of the
engine RPM drop initiated by the shift. If the actual shift time is longer than the calibrated
desired shift time, a soft feel or slow engagement, then the TCM decreases current to the pressure
control (PC) solenoid in order to increase line pressure for the next, same, upshift under identical
conditions. If the actual shift time is shorter than the calibrated desired shift time, a firm
engagement, then the TCM increases current to the PC solenoid in order to decrease line pressure
for the next, same, upshift under identical conditions.

The purpose of the adapt function is to automatically compensate the shift quality for the various
vehicle shift control systems. It is a continuous process that will help to maintain optimal shift

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

quality throughout the life of the vehicle.

Clearing Transmission Adaptive Pressure (TAP)

Transmission adaptive pressure (TAP) information is displayed and may be reset using a scan
tool.

The adapt function is a feature of the TCM that either adds or subtracts line pressure from a
calibrated base line pressure in order to compensate for normal transmission wear. The TAP
information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell
represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16
is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative
numbers. This indicates that the TCM has adjusted line pressure at or below the calibrated base
line pressure.

Updating TAP information is a learning function of the TCM designed to maintain acceptable
shift times. It is not recommended that TAP information be reset unless one of the following
repairs has been made:

Transmission overhaul or replacement

Repair or replacement of an apply or release component, clutch, band, piston, servo

Repair or replacement of a component or assembly which directly affects line pressure

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the
TCM will need to relearn TAP values. Transmission performance may be affected as new TAPs
are learned. Learning can only take place when the TCM has determined that an acceptable shift
has occurred. The TCM must also relearn TAP values if it is replaced.

TRANSMISSION INDICATORS AND MESSAGES (TCM)

The following transmission-related indicators and messages may be displayed on the instrument
panel cluster (IPC). For a complete listing and description of all vehicle indicators and messages,
refer to Indicator/Warning Message Description and Operation .

"Change Trans Fluid"

The IPC illuminates the "change trans fluid" message when the transmission control module
(TCM) determines that the transmission oil should be changed. The TCM sends a message to
the IPC requesting illumination. The select button will allow this message to clear it from
the DIC display.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

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Chevrolet Silverado / GMC Sierra. Manual - part 1172