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Home >> Acura >> 2012 >> TL Base >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission >> System Description >> Electronic Control System >> Shift Control
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Shift Control

The PCM instantly determines which gear should be selected by various inputs from sensors and switches, and it actuates the solenoid valves to control gear selection.

Shift solenoid valve:

Shift solenoid valves A, B, and C switch to the hydraulic pressure supply circuit to the clutch. Shift solenoid valves A, B, and C are normally closed (ON-OPEN/OFF-CLOSE); the normally closed solenoid valve port opens to allow ATF to pass through when the PCM turns it ON, and the port closes, blocking fluid flow when turned OFF.

A/T clutch pressure control solenoid valve:

A/T clutch pressure control solenoid valves A, B, C, and D apply hydraulic pressure to each clutch via the hydraulic valve body circuit. A/T clutch pressure control solenoid valve D supplies hydraulic pressure to the torque converter clutch. A/T clutch pressure control solenoid valves A, B, C, and D are normally closed (ON-OPEN/OFF-CLOSE); the normally closed solenoid valve port opens to allow ATF to pass through when the PCM turns it ON, and the port closes, blocking fluid flow when turned OFF. These solenoid valves are controlled by current and are duty controlled depending on the vehicle speed and the throttle position.

Line pressure solenoid valve:

Line pressure solenoid valve A controls the hydraulic pressure in the hydraulic control system valve bodies of the automatic transmission. Line pressure solenoid valve A is normally closed (ON-OPEN/OFF-CLOSE); the normally closed solenoid valve port opens to allow ATF to pass through when the PCM turns it ON, and the port closes, blocking fluid flow when turned OFF.

The combination of driving signals to solenoid valves for each gear is in the following table.

Shift Lever Position P R N D, S
1st 2nd 3rd 4th 5th 6th
Shift solenoid valve A ON OFF ON ON ON OFF OFF OFF OFF
Shift solenoid valve B OFF OFF OFF ON ON ON ON or OFF ON or OFF OFF
Shift solenoid valve C ON ON OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF
Line pressure solenoid valve A ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF
A/T clutch pressure control solenoid valve A OFF OFF OFF OFF ON OFF OFF ON OFF
A/T clutch pressure control solenoid valve B OFF OFF OFF OFF OFF ON OFF OFF ON
A/T clutch pressure control solenoid valve C OFF OFF OFF OFF OFF OFF ON OFF OFF
A/T clutch pressure control solenoid valve D OFF ON OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF ON or OFF