## Automatic Transmission

#### System description (cont'd)

14-55

Hydraulic Flow

As the engine turns, the ATF pump starts to operate. Automatic transmission fluid (ATF) is drawn through the ATF strainer and discharged into the hydraulic circuit. Then, ATF flowing from the ATF pump becomes line pressure that's regulated by the regulator valve. Torque converter pressure from the regulator valve enters the torque converter through the lock-up shift valve and it is discharged from the torque converter. The torque converter check valve prevents torque converter pressure from rising.

The PCM controls the shift solenoid valves A and B ON and OFF and shift solenoid valves A and B apply modulator pressure to the shift valves. Applying modulator pressure to the shift valves moves the position of the shift valve and switches the port of hydraulic pressure. The PCM also controls the A/T clutch pressure control solenoid valves A and B. The A/T clutch pressure control solenoid valve A regulates linear solenoid pressure and applies linear solenoid pressure to the CPC valves. The CPC valve regulates CPC pressure and controls to shift smoothly between upper and lower gears.

Hydraulic pressure at the port is as follows:

PORT NO. | DESCRIPTION OF PRESSURE | PORT NO. | DESCRIPTION OF PRESSURE
1 | LINE | 15 | 1ST-HOLD CLUTCH
1' | LINE | 16 | 1ST-HOLD CLUTCH
1" | LINE | 17 | 1ST-HOLD CLUTCH
2 | LINE | 18 | 1ST-HOLD CLUTCH
3 | LINE | 20 | 2ND CLUTCH
3' | LINE | 20A | 2ND ACCUMULATOR
3" | LINE | 30 | 3RD CLUTCH
4 | LINE | 40 | 4TH CLUTCH
4' | LINE | 41 | 4TH CLUTCH
4" | LINE | 56 | LINEAR SOL A
5 | CPC | 90 | TORQUE CONVERTER
6 | MODULATOR | 91 | TORQUE CONVERTER
6A | MODULATOR (SH A) | 92 | TORQUE CONVERTER
6B | MODULATOR (SH B) | 93 | ATF COOLER
6C | MODULATOR (LC A) | 94 | TORQUE CONVERTER
6E | LINEAR SOL B | 95 | LUBRICATION
6E' | LINEAR SOL B | 96 | TORQUE CONVERTER
7 | LINE | 97 | TORQUE CONVERTER
8 | LINE/CPC | 99 | SUCTION
9 | LINE | X | DRAIN
10 | 1ST CLUTCH | HIX | HIGH POSITION DRAIN

Key to abbreviations:

- CPC: Clutch pressure control
- SH A: Shift solenoid valve A
- SH B: Shift solenoid valve B
- LC A: Torque converter clutch solenoid valve
- LINEAR SOL A: A/T clutch pressure control solenoid valve A
- LINEAR SOL B: A/T clutch pressure control solenoid valve B