Hummer H2. Manual — part 2379

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Automatic transmission fluid pressure (TFP) manual valve position switch

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Automatic transmission fluid temperature (TFT) sensor

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Vehicle speed sensor assembly

For more information, refer to Electronic Component Description .

TRANSMISSION ADAPTIVE FUNCTIONS

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 PCM 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 PCM 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 PCM 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 PCM 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 PCM 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 PCM 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 PCM 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 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 PCM 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 PCM has adjusted line pressure at or below
the calibrated base line pressure.

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

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2

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Transmission overhaul or replacement

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

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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 PCM will
need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. Learning can
only take place when the PCM has determined that an acceptable shift has occurred. The PCM must also relearn
TAP values if it is replaced.

ELECTRONIC COMPONENT DESCRIPTION

1-2 and 2-3 Shift Solenoid Valves

Fig. 488: 1-2 and 2-3 Shift Solenoid Valves
Courtesy of GENERAL MOTORS CORP.

The 1-2 and 2-3 shift solenoid valves (also called A and B solenoids) are identical devices that control the
movement of the 1-2 and 2-3 shift valves. The 3-4 shift valve is not directly controlled by a shift solenoid. The

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2

solenoids are normally-open exhaust valves that work in 4 combinations to shift the transmission into different
gears.

The powertrain control module (PCM) energizes each solenoid by grounding the solenoid through an internal
quad driver. This sends current through the coil winding in the solenoid and moves the internal plunger out of
the exhaust position. When ON, the solenoid redirects fluid to move a shift valve.

The PCM-controlled shift solenoids eliminate the need for TV and governor pressures to control shift valve
operation.

3-2 Shift Solenoid Valve Assembly

Fig. 489: 3-2 Shift Solenoid Valve Assembly
Courtesy of GENERAL MOTORS CORP.

The 3-2 shift solenoid valve assembly is a normally-closed, 3-port, ON/OFF device that is used in order to
improve the 3-2 downshift. The solenoid regulates the release of the 3-4 clutch and the 2-4 band apply.

Transmission Pressure Control Solenoid

IMPORTANT: The manual valve hydraulically can override the shift solenoids. Only in D4 do

the shift solenoid states totally determine what gear the transmission is in. In
the other manual valve positions, the transmission shifts hydraulically and the
shift solenoid states CATCH UP when the throttle position and the vehicle
speed fall into the correct ranges.

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2

Fig. 490: Transmission Pressure Control Solenoid
Courtesy of GENERAL MOTORS CORP.

The transmission pressure control solenoid is an electronic pressure regulator that controls pressure based on the
current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal
valve which varies pressure to the pressure regulator valve.

The PCM controls the pressure control solenoid by commanding current between 0.1-1.1 amps. This changes
the duty cycle of the solenoid, which can range between 5-95 percent, typically less than 60 percent. High
amperage (1.1 amps) corresponds to minimum line pressure, and low amperage (0.1 amp) corresponds to
maximum line pressure, if the solenoid loses power, the transmission defaults to maximum line pressure.

The PCM commands the line pressure values, using inputs such as engine speed and throttle position sensor
voltage.

The pressure control solenoid takes the place of the throttle valve or the vacuum modulator that was used on
past model transmissions.

Torque Converter Clutch Solenoid Valve

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E (Introduction) - Hummer H2