Hummer H2. Manual - part 2361

Reverse input fluid exhausts from the TFP manual valve position switch. With no other fluid routed to it, the 
TFP manual valve position switch signals the PCM that the transmission is operating in either Park or Neutral.

IMPORTANT: In Park, Reverse and Neutral the shift solenoid valves are shown energized. 

This is the normal operating state when the vehicle is stationary or at low 
vehicle speeds. However, the PCM will change the shift solenoid valve states 
depending on the vehicle speed. For example, if Neutral is selected when the 
transmission is operating in Second Gear, the shift solenoid valves will remain 
in a Second Gear state. However, with the manual valve blocking line pressure, 
the shift solenoid valve states do not affect transmission operation in Park, 
Reverse and Neutral.

 

2004 Hummer H2 

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

  

Fig. 465: Neutral - Engine Running 
Courtesy of GENERAL MOTORS CORP.

 

2004 Hummer H2 

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

  

OVERDRIVE RANGE, FIRST GEAR 

When the gear selector lever is moved to the Overdrive position, from the neutral position, the following 
changes occur to the transmission's hydraulic and electrical systems: 

Manual Valve 

Line pressure flows through the manual valve and fills the D4 fluid circuit. All other fluid circuits remain empty 
with the manual valve in the Overdrive position. 

Forward Clutch Applies 

or  

Forward Clutch Accumulator Checkball (#12) 

D4 fluid pressure seats the checkball and is orificed (#22) into the forward clutch feed fluid circuit. This orifice 
helps control the forward clutch apply rate. 

Forward Clutch Accumulator Piston 

Forward clutch feed fluid pressure moves the piston against spring force. This action absorbs some of the initial 
increase of forward clutch feed fluid pressure to cushion the forward clutch apply. 

Forward Clutch Abuse Valve 

D4 fluid pressure acts on the valve opposite of spring force. At engine speeds greater than idle, D4 fluid 
pressure increases and moves the valve against spring force (as shown). D4 fluid can then quickly fill the 
forward clutch feed fluid circuit, thereby bypassing the control of orifice #22 and providing a faster apply of the 
forward clutch. Otherwise, with increased throttle opening and engine torque, the clutch may slip during apply. 

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Assembly 

D4 fluid pressure is routed to the TFP manual valve position switch and closes the normally open D4 fluid 
pressure switch. This signals the PCM that the transmission is operating in Overdrive range. 

1-2 Shift Solenoid (SS) Valve 

Energized (ON) as in Neutral, the normally open solenoid is closed and blocks signal A fluid from exhausting 
through the solenoid. This maintains pressure in the signal A fluid circuit. 

2-3 Shift Solenoid (SS) Valve 

Energized (ON) as in Neutral, the normally open solenoid is closed and blocks signal B fluid from exhausting 
through the solenoid. This maintains signal B fluid pressure at the solenoid end of the 2-3 shift valve. 

2-3 Shift Valve Train 

 

2004 Hummer H2 

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

  

Signal B fluid pressure at the solenoid end of the 2-3 shift valve holds the valve train in the downshifted 
position against AFL fluid pressure acting on the 2-3 shift valve. In this position, the 2-3 shuttle valve blocks 
AFL fluid from entering the D432 fluid circuit. The D432 fluid circuit is open to an exhaust port past the valve. 

1-2 Shift Valve 

Signal A fluid pressure holds the valve in the downshifted position against spring force. In the First gear 
position, the valve blocks D4 fluid from entering the 2nd fluid circuit. 

Accumulator Valve 

Biased by torque signal fluid pressure, spring force and orificed accumulator fluid pressure at the end of the 
valve, the accumulator valve regulates D4 fluid into accumulator fluid pressure. Accumulator fluid is routed to 
both the 1-2 and 3-4 accumulator assemblies in preparation for the 1-2 and 3-4 upshifts respectively. 

Rear Lube (All Except Y-Car) 

D4 fluid is routed through an orifice cup plug (#24) in the rear of the transmission case to feed the rear lube 
fluid circuit. 

Pressure Control (PC) Solenoid Valve 

Remember that the PC solenoid valve continually varies torque signal fluid pressure in relation to throttle 
position and vehicle operating conditions. This provides a precise control of line pressure. 

3-2 Control Solenoid Valve 

The PCM keeps the solenoid OFF in First gear and the normally closed solenoid blocks filtered AFL fluid from 
entering the 3-2 signal fluid circuit. 

Torque Converter Clutch PWM Solenoid Valve 

In first gear, at approximately 6 mph, the PCM operates the TCC PWM solenoid valve at approximately a 90 
percent duty cycle. This opens the AFL fluid circuit, to fill the converter clutch signal fluid circuit through the 
#9 orifice, and flows to the isolator valve. The CC signal fluid pressure, acting on the isolator valve, will move 
the regulated apply valve towards the closed position. Regulated line pressure is now routed into the regulated 
apply circuit, and flows to the closed converter clutch valve, and is blocked from entering the converter clutch 
apply circuit. Regulated apply fluid is routed through the #8 orifice to the front of the regulated apply valve, and 
regulates the line pressure entering the regulated apply circuit, in response to the CC signal fluid acting on the 
isolator valve. 

 

2004 Hummer H2 

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