Distribution of Hydraulic Pressure

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

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

The powertrain control module (PCM) controls the shift solenoid valves ON and OFF. The shift solenoid valves control shift solenoid pressure to the shift valves. Applying shift solenoid pressure to the shift valves moves the position of the shift valve, and switches the port of hydraulic pressure. The PCM also controls the automatic transmission clutch pressure control (AT CPC) solenoid valves A and B.

The AT CPC solenoid valves A and B regulate the AT CPC solenoid pressure and apply the AT CPC solenoid pressure to CPC valves A and B. When shifting between upper gear and lower gear, the clutch is engaged by pressure from the CPC pressure mode.

The PCM controls one of the shift solenoid (SS) valves to move the position of the shift valve. This movement switches the port of the CPC and line pressure. Line pressure is then applied to the clutch, and the CPC pressure is intercepted.

When shifting is completed, the clutch is engaged with line pressure.

Hydraulic Pressure at the Ports

Port No.	Type of Pressure	Port No.	Type of Pressure	Port No.	Type of Pressure
1	Line	5N	CPC A or Line	56	LS A
2	Line	5D	CPC B or Line	57	LS B
3	Line	5G	CPC B or Line	58	LS C
3'	Reverse CPC or Line	5K	CPC B or Line	90	Torque Converter
3"	Reverse CPC or Line	6	Modulate	90'	Torque Converter
4	Line	SA	SH A	91	Torque Converter
4'	Line	SB	SH B	91'	Torque Converter
4"	Line	SC	SH C	92	Torque Converter
4A	CPC A	LA	LC A	93	ATF cooler
4B	CPC B	9	Line	94	Torque Converter
4C	CPC C	10	1st Clutch	95	Lubrication
5B	CPC A	15	1st Hold Clutch	95'	Lubrication
5C	CPC B	20	2nd Clutch	96	Torque Converter
5H	CPC B	25	Line	97	Torque Converter
5J	CPC B	30	3rd Clutch	99	Suction
5A	CPC A or Line	40	4th Clutch	X	Drain
5E	CPC A or Line	50	5th Clutch	HX	High Position Drain
5F	CPC A or Line	51	5th Clutch	hX	High Position drain
5M	CPC A or Line	55	CPC C or Line	AX	Air Drain
CPC: Clutch Pressure Control Pressure SH: Shift Solenoid Pressure LS A: AT CPC Solenoid A Pressure LS B: AT CPC Solenoid B Pressure LS C: AT CPC Solenoid C Pressure LC: Torque Converter Clutch Solenoid Pressure