Hummer H3. Manual — part 874

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

These components are used to increase the exhaust rate of 3rd accumulator fluid, as needed,
depending on the vehicle speed.

The 3-2 control solenoid valve is a normally closed On/Off solenoid controlled by the PCM. The
PCM controls the solenoid state during a 3-2 downshift according to vehicle speed.

Low Speed

At lower vehicle speeds, the PCM operates the 3-2 control solenoid valve in the Off
position.

In the Off position the solenoid blocks actuator feed limit fluid pressure from the 3-2
control valve.

With no actuator feed limit fluid pressure, the 3-2 control valve spring force keeps the valve
open to allow a faster exhaust of 3rd accumulator fluid through orifice #14 into the 3-4
clutch fluid circuit.

A faster exhaust of the 3rd accumulator exhaust fluid provides a faster apply of the 2-4
band, as needed at lower vehicle speeds.

High Speed

At high vehicle speed, the PCM operates the 3-2 control solenoid valve in the On position
allowing actuator feed limit fluid to pass through the solenoid. This pushes the 3-2 control
valve into the closed position.

This action permits a slow apply of the 2-4 band by blocking off 3rd accumulator exhaust
fluid from entering the 3-4 clutch fluid circuit through orifice #14.

This allows the engine speed to easily come up to the necessary RPM before the 2-4 band is
applied.

3rd Accumulator Exhaust Checkball (#7)

After the downshift is completed, the #7 checkball unseats and allows the residual fluid in the 3rd
accumulator fluid circuit to exhaust.

Pressure Control (PC) Solenoid Valve

Remember that the PC solenoid valve continually adjusts torque signal fluid in relation to the
various PCM input signals (mainly the throttle position).

2007 Hummer H3

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

Fig. 494: Overdrive Range, 3-2 Downshift Hydraulic Circuit Diagram
Courtesy of GENERAL MOTORS CORP.

MANUAL THIRD GEAR

A manual 4-3 downshift is available to increase vehicle performance when the use of only three
gear ratios is desired. Manual Third gear range also provides engine braking in Third gear when
the throttle is released. A manual 4-3 downshift is accomplished by moving the selector lever into
the Manual Third (D) position. This moves the manual valve and immediately downshifts the
transmission into Third gear. Refer to Overdrive Range, 4-3 Downshift for a complete
description of a 4-3 downshift. In Manual Third, the transmission is prevented, both hydraulically
and electronically, from shifting into Fourth gear. The following information explains the
additional changes during a manual 4-3 downshift as compared to a forced 4-3 downshift.

Manual Valve

The selector lever moves the manual shaft and manual valve into the Manual Third position (D).
This allows line pressure to enter the D3 fluid circuit.

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly

D3 fluid is routed to the TFP manual valve position switch and opens the normally closed D3

2007 Hummer H3

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

fluid pressure switch. The combination of the opened D3 switch and the closed D4 switch signals
the PCM that the transmission is operating in Manual Third.

1-2 Shift Solenoid (SS) Valve

When Manual Third is selected, the PCM de-energizes the 1-2 SS valve to immediately downshift
the transmission into Third gear. This electronically prevents Fourth gear.

3-4 Shift Valve

D3 fluid pressure assists spring force to keep the valve in the downshifted position against the
signal A fluid circuit. In this position, the valve blocks 3-4 signal fluid and the 4th signal fluid
circuit is open to an exhaust port past the valve. Therefore, with D3 fluid pressure assisting spring
force, Fourth gear is hydraulically prevented.

2-3 Shift Valve Train

With the 2-3 SS valve de-energized and open, actuator feed limit (AFL) fluid acting on the 2-3
shift valve holds both valves in the upshifted position. This allows D3 fluid to feed the overrun
fluid circuit through the 2-3 shift valve.

Overrun Clutch Feed Checkball (#5)

Overrun fluid pressure seats the ball against the empty D2 fluid circuit.

Overrun Clutch Control Checkball (#6)

Overrun fluid pressure seats the #6 checkball and is orificed (#20) to fill the overrun clutch feed
fluid circuit. This orifice controls the overrun clutch apply rate.

3-4 Relay Valve and 4-3 Sequence Valve

4th signal fluid pressure is exhausted from the end of the 3-4 relay valve. Overrun clutch feed
fluid pressure assists spring force and closes both valves. This allows overrun clutch feed fluid to
flow through the 4-3 sequence valve and fill the overrun clutch fluid circuit.

Overrun Clutch Piston

Overrun clutch fluid pressure moves the piston to apply the overrun clutch plates. The overrun
clutch plates provide engine compression braking in Manual Third - Third Gear.

Overrun Clutch Air Bleed Checkball

This ball and capsule is located in the overrun clutch fluid circuit in the oil pump. It allows air to

2007 Hummer H3

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

exhaust from the circuit as fluid pressure increases and also allows air into the circuit to displace
the fluid when the clutch releases.

Torque Converter Clutch and Torque Converter Clutch PWM Solenoid Valve

The PCM de-energizes the TCC solenoid valve and operates the duty cycle of the TCC PWM
solenoid valve to release the converter clutch prior to downshifting, (assuming the converter
clutch is applied in Overdrive Range-Fourth Gear when Manual Third is selected). The PCM will
re-apply the converter clutch in Manual Third-Third Gear when proper driving conditions have
been met.

Pressure Control (PC) Solenoid Valve

The PC solenoid valve operates in the same manner as Overdrive Range, regulating in response to
throttle position and other vehicle operating conditions.

Manual Third - First and Second Gears: Overrun Clutch Released

In Manual Third, the transmission upshifts and downshifts normally between First, Second and
Third gears. However, in First and Second gears, the 2-3 SS valve is energized and the 2-3 shift
valve train is in the downshifted position. The 2-3 shift valve blocks D3 fluid from entering the
overrun fluid circuit and opens the overrun fluid circuit to an exhaust port at the valve. This
prevents overrun clutch apply and engine compression braking in Manual Third-First and Second
Gears.

2007 Hummer H3

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