Hummer H2. Manual - part 2364

circuit. 

3-4 Accumulator Assembly 

3-4 accumulator fluid pressure moves the 3-4 accumulator piston against spring force and orificed accumulator 
fluid pressure. This action absorbs initial 4th clutch apply fluid pressure in order to cushion the 2-4 band apply. 
Remember that both of the 3-4 accumulator and 4th fluid circuits are fed by servo feed fluid. As 3-4 
accumulator fluid fills the accumulator, any air in the system will exhaust through office #19. This piston 
movement forces some orificed accumulator fluid out of the 3-4 accumulator assembly. 

3-4 Accumulator Checkball (#1) 

The accumulator fluid forced from the accumulator unseats the #1 checkball and enters the accumulator fluid 
circuit. This fluid is routed to the accumulator valve. This is shown by the arrow directions in the fluid circuit. 

Accumulator Valve 

Accumulator fluid forced from the 3-4 accumulator is orificed to the end of the accumulator valve. This fluid 
pressure, in addition to spring force and torque signal fluid pressure, regulates the exhaust of excess 
accumulator fluid pressure through the middle of the valve. This regulation helps control the 2-4 band apply 
feel. 

3-2 Control Solenoid Valve and 3-2 Control Valve 

The solenoid remains open and routes AFL fluid into the 3-2 signal fluid circuit. 3-2 signal fluid pressure holds 
the 3-2 control valve against spring force, thereby blocking the 3rd accumulator and 3-4 clutch fluid circuits. 

Torque Converter Clutch Applies 

TCC Solenoid Valve 

When operating conditions are appropriate, the PCM energizes the normally open TCC solenoid valve. This 
closes the solenoid, blocks the converter feed fluid from exhausting, and creates pressure in the converter feed 
fluid circuit at the converter clutch apply valve and TCC solenoid valve. 

Converter Clutch Apply Valve 

Converter feed fluid pressure moves the valve against spring force and into the apply position. In this position, 
release fluid is open to an exhaust port, and regulated apply fluid fills the apply fluid circuit. Converter feed 
fluid is routed through the converter clutch apply valve to feed the cooler fluid circuit. 

Torque Converter 

Release fluid from behind the pressure plate exhausts through the end of the turbine shaft. Apply fluid pressure 
is routed between the converter hub and stator shaft where it enters the torque converter. This fluid applies the 
converter clutch against the converter cover and keeps the converter filled with fluid. 

TCC Apply Checkball (#9) 

 

2004 Hummer H2 

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

  

Release fluid, exhausting from the converter, seats the #9 checkball located in the end of the turbine shaft, and 
is orificed around the ball. Orificing the exhausting release fluid controls the converter clutch apply rate, along 
with the TCC PWM solenoid valve. 

TCC PWM Solenoid Valve 

The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls the regulated apply 
valve position. This is done through the use of pulse width modulation (duty cycle operation). The solenoid 
duty cycle is controlled by the PCM in relation to vehicle operating conditions and regulates actuator feed limit 
(AFL) fluid into the CC signal circuit, through the #9 orifice, and to the isolator valve. This controls line 
pressure flow through the regulated apply valve, into the regulated apply circuit, and provides a smooth 
engagement of the TCC. 

 

2004 Hummer H2 

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

  

Fig. 469: Overdrive Range, Fourth Gear - TCC Applied 
Courtesy of GENERAL MOTORS CORP.

 

2004 Hummer H2 

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

  

OVERDRIVE RANGE, 4-3 DOWNSHIFT

When the transmission is operating in fourth gear, a forced 4-3 downshift occurs if there is a significant increase 
in throttle position. At minimum throttle, the vehicle speed decreases gradually (coastdown) and the PCM 
commands a 4-3 downshift. The PCM also initiates a forced 4-3 downshift when the throttle position remains 
constant but engine load is increased, such as driving up a steep incline. To achieve a 4-3 downshift, the PCM 
de-energizes the 1-2 shift solenoid valve and the following changes occur to the transmission's electrical and 
hydraulic systems: 

1-2 Shift Solenoid (SS) Valve 

De-energized by the PCM, the normally open solenoid opens and signal A fluid exhausts through the solenoid. 

1-2 Shift Valve 

As in Fourth gear, D432 fluid pressure and spring force hold the valve in the upshift position. 

2-4 Band Releases 

3-4 Shift Valve 

With the signal A fluid pressure exhausted, the spring force moves the valve into the downshift position. In this 
position, the valve blocks the 3-4 signal fluid and the 4th signal fluid exhausts past the valve. 

3-4 Relay Valve and 4-3 Sequence Valve 

These valves control the timing of the 2-4 band release. With the 4th signal fluid pressure exhausted, the 3-4 
accumulator fluid pressure moves the 3-4 relay valve into the third gear position. This opens the 3-4 
accumulator fluid to an orificed exhaust (#5) past the 3-4 relay valve (shown by red arrows). Because the 
exhaust is orificed, the 3-4 accumulator fluid pressure momentarily holds the 4-3 sequence valve against spring 
force before completely exhausting. 

When the exhausting 3-4 accumulator fluid pressure decreases sufficiently, the spring force moves the 4-3 
sequence valve into the third gear position as shown. This opens both the 3-4 accumulator and the 4th fluid 
circuits to a quick exhaust past the 4-3 sequence valve. In this position the valve blocks the 2nd fluid from 
entering the servo feed fluid circuit. 

2-4 Servo Assembly 

The 4th fluid exhausts from the 4th apply piston in the servo assembly. The apply pin spring moves the 4th 
apply piston and the apply pin in order to release the band from the reverse input drum and shift the 
transmission into third gear. 

3-4 Accumulator Assembly 

The 3-4 accumulator fluid exhausts from the 3-4 accumulator piston. The orificed accumulator fluid pressure 
and the spring force move the piston into a third gear position.

 

2004 Hummer H2 

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