Hummer H3. Manual — part 876

2-3 Shift Solenoid (SS) Valve

In both first and second gears, this solenoid is energized and maintains the signal B fluid pressure
at the solenoid end of the 2-3 shift valve train.

2-3 Shift Valve Train

Held in the downshift position by the signal B fluid pressure from the solenoid, the valve train
blocks the AFL fluid from entering the D432 fluid circuit. The D432 fluid circuit is open to
exhaust past the valve.

1-2 Shift Solenoid (SS) Valve

Below approximately 48 to 56 km/h (30 to 35 mph) the PCM energizes the normally open
solenoid. This blocks the signal A fluid pressure from exhausting through the solenoid and creates
the pressure in the signal A fluid circuit. Above this speed, the PCM keeps the solenoid de-
energized and the transmission operates in manual first-second gear.

1-2 Shift Valve

Signal A fluid pressure moves the valve against the spring force and into the downshift position.
In this position, Lo fluid from the manual valve is routed into the Lo/1st fluid circuit and D4 fluid
is blocked from entering the 2nd fluid circuit. The 2nd fluid exhausts through an orifice and an
annulus exhaust port past the valve. This orifice (#26) helps control the 2-4 band release during a
2-1 downshift.

2-4 Band Releases

2-4 Servo Assembly

The 2nd clutch fluid, which was fed by the 2nd fluid, exhausts from the servo. This allows the
spring force from the servo cushion and the servo return springs to move the 2nd apply piston and
apply the pin to release the 2-4 band. These spring forces help control the 2-4 band release.

1-2 Accumulator Assembly

The 2nd clutch fluid also exhausts from the 1-2 accumulator assembly. The spring force and the
accumulator fluid pressure move the accumulator piston to assist the 2nd clutch fluid exhaust.

Accumulator Valve

As the accumulator fluid is filling the 1-2 accumulator assembly, the accumulator valve regulates
the D4 fluid into the accumulator fluid circuit. This regulation, biased by torque signal fluid
pressure and spring force, helps control the movement of the 1-2 accumulator piston. The 2nd

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3

clutch fluid exhaust and the 2-4 band release.

1-2 Upshift Checkball (#8)

Exhausting the 2nd clutch fluid pressure unseats the ball and is routed through the 2nd fluid
circuit.

Lo and Reverse Clutch Applies

Lo Overrun Valve

The Lo/1st fluid is regulated through the lo overrun valve and into the Lo/reverse fluid circuit in
order to control the lo and reverse clutch apply.

Lo and Reverse Piston

The Lo/reverse fluid pressure acts on the inner area of the piston in order to move the piston and
in order to apply the lo and reverse clutch plates.

Overrun Clutch Applied

The overrun clutch remains applied in manual first in order to provide engine compression
braking.

Pressure Control (PC) Solenoid Valve

Similar to manual second, the PCM output signal to the PC solenoid valve increases the operating
range of the torque signal fluid pressure. This provides the increased line pressure for the
additional torque requirements during the engine compression braking and the increased engine
loads.

3-2 Downshift Control Solenoid Valve and the 3-2 Control Valve

In first gear the solenoid is OFF, the AFL fluid is blocked by the solenoid and the 3-2 signal fluid
exhausts through the solenoid and the spring force opens the 3-2 control valve.

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3

Fig. 497: Manual First Gear Hydraulic Circuit Diagram
Courtesy of GENERAL MOTORS CORP.

FLUID PASSAGES

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3

Fig. 498: Pump Body Fluid Passages (Pump Cover Side)
Courtesy of GENERAL MOTORS CORP.

Callouts For Fig. 498

Callout

Component Name

1

Suction (intake)

2

Decrease

2

Decrease

3

Line

3

Line

3

Line

2007 Hummer H3

2007 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - H3