Honda Civic. Manual — part 182

When starting off in reverse gear, the PCM turns shift solenoid valves B and C ON.
Shift solenoid valve A remains OFF, and D remains ON. Shift solenoid valve B is
turned ON, and shift solenoid valve B pressure (SB) is applied to the right end of
shift valve B. Shift valve B is moved to the right side to switch A/T clutch pressure
control solenoid valve A pressure (55') port to line pressure (1B) port leading to the
5th clutch. The 5th clutch is engaged with the line pressure mode.

Reverse Inhibitor Control

When R is selected while the vehicle is moving forward at speeds over 6 mph (10
km/h), the PCM turns shift solenoid valves A and C ON, and shift solenoid valves
B and D OFF. Shift solenoid valve D is kept OFF, and shift valve D is kept in the
left side to cover line pressure (3) port leading to the servo valve. The servo valve is
kept in the forward position. Shift solenoid valve A is turned ON, shift valve A is
moved to the right side and covers the port to stop line pressure (1 A) leading to the
5th clutch. The servo valve is not applied line pressure, the 5th clutch is not applied
5th clutch pressure, as a result, power is not transmitted to the reverse direction.

NOTE:

When used, "left" or "right" indicates direction on the
hydraulic circuit.

2008 Honda Civic LX

2006-08 TRANSMISSION Automatic Transmission - Civic (Except Hybrid)

Fig. 54: Hydraulic Fuel Pressure Flow Diagram (R Position - Driving In
Reverse Gear)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

P Position

The manual valve is moved into the P position, line pressure (1) becomes line
pressure (1), (3), and (7) at the manual valve. The PCM turns shift solenoid valve D
ON, and shift solenoid valves A, B, and C OFF. Shift solenoid valve D pressure
(SD) is applied to the left end of shift valve D, and shift valve D is moved to the
right side to uncover line pressure (3) port leading to the servo valve. Line pressure
(3') from shift valve D flows to the servo valve, and pushes the servo valve to the
reverse position. Line pressure (1) is intercepted at cut valve B, line pressure (1B) is
intercepted at shift valve B, and hydraulic pressure is not applied to the clutches.

NOTE:

When used, "left" or "right" indicates direction on the
hydraulic circuit.

2008 Honda Civic LX

2006-08 TRANSMISSION Automatic Transmission - Civic (Except Hybrid)

Fig. 55: Hydraulic Fuel Pressure Flow Diagram (P Position)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Lock-up System

The lock-up mechanism of the torque converter clutch operates in D (2nd, 3rd, 4th,
and 5th gears) and D3 (2nd and 3rd gears). The pressurized fluid is drained from the
back of the torque converter through a fluid passage, causing the torque converter
clutch piston to be held against the torque converter cover. As this takes place, the
mainshaft rotates at the same speed as the engine crankshaft. Together with the
hydraulic control, the PCM optimizes the timing and the amount of ATF the lock-
up mechanism receives. When shift solenoid valve D is turned on by the PCM, shift
solenoid valve D pressure turns the lock-up shift valve lock-up on and off. A/T
clutch pressure control solenoid valve A and the lock-up control valve control the
volume of lock-up.

Torque Converter Clutch Lock-up ON (Engaging Torque Converter Clutch)

2008 Honda Civic LX

2006-08 TRANSMISSION Automatic Transmission - Civic (Except Hybrid)

Fluid in the chamber between the torque converter cover and the torque converter
clutch piston is drained off, and fluid entering from the chamber between the pump
and the stator exerts pressure through the torque converter clutch piston against the
torque converter cover. The torque converter clutch piston engages with the torque
converter cover; the torque converter clutch locks-up, and the mainshaft rotates at
the same as the engine.

Fig. 56: Torque Converter Clutch Lock-Up On Diagram (Engaging Torque
Converter Clutch)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Torque Converter Clutch Lock-up OFF (Disengaging Torque Converter Clutch)

Fluid entered from the chamber between the torque converter cover and the torque
converter clutch piston passes through the torque converter and goes out from the
chambers between the turbine and the stator, and the pump and the stator. As a
result, the torque converter clutch piston moves away from the torque converter
cover, and the torque converter clutch lock-up is released.

2008 Honda Civic LX

2006-08 TRANSMISSION Automatic Transmission - Civic (Except Hybrid)