As vehicle speed increases and other operating conditions are appropriate, the PCM de-energizes the 1-2 shift solenoid in order to shift the transmission to second gear

De-energized (turned OFF) by the PCM, the normally open solenoid opens and signal A fluid exhausts through the solenoid.

Important: The actuator feed limit (AFL) fluid continues to feed the signal A fluid circuit through orifice #25. However, the exhaust port through the solenoid is larger than orifice #25 in order to prevent a pressure buildup in the signal A fluid circuit. Exhausting signal A fluid is represented by the blue arrows.

Energized (ON) as in first gear, the 2-3 shift solenoid blocks AFL fluid from exhausting through the solenoid. This maintains AFL fluid pressure at the solenoid end of the 2-3 shift valve.

Without signal A fluid pressure, spring force moves the valve into the upshift position. D4 fluid is routed through the valve and fills the 2nd fluid circuit.

The 2nd fluid pressure seats the #8 checkball, flows through orifice #16, and fills the 2nd clutch fluid circuit. This orifice helps control the 2-4 band apply rate.

The 2nd clutch fluid pressure moves the #8 checkball, flows through orifice #16 and fills the 2nd clutch fluid circuit. This orifice helps to control the 2-4 band apply rate.

The 2nd clutch fluid pressure also moves the 1-2 accumulator piston against the spring force and the accumulator fluid pressure. This action absorbs the initial 2nd clutch fluid pressure in order to cushion the 2-4 band apply rate. Also, the movement of the 1-2 accumulator piston forces some accumulator fluid out of the accumulator assembly. This accumulator fluid is routed back to the accumulator valve.

The accumulator fluid forced out of the 1-2 accumulator is orificed (#30) to the end of the accumulator valve. This pressure moves the valve against the spring force and the torque signal fluid pressure in order to regulate the exhaust of excess accumulator fluid. This regulation provides additional control for the 2-4 band apply rate. The oil circuit shows the exhaust of the accumulator fluid during the shift by the arrow directions in the accumulator fluid circuit.

The AFL fluid pressure from the 2-3 shift solenoid holds the valve train in the downshift position. The 2nd fluid is routed through the 2-3 shuttle valve and fills the servo feed fluid circuit.

Spring force holds these valves in the downshift position (first, second and third gear positions). The 2nd fluid is blocked by the 3-4 relay valve and the servo feed fluid is blocked by both valves in preparation for a 3-4 upshift.

Spring force holds the valve closed, blocking the 2nd fluid and the 2nd clutch fluid. This valve is used in order to help control the 3-2 downshift.

In second gear, the PCM operates the normally closed solenoid at approximately a 90% duty cycle. This opens the AFL fluid circuit to fill the 3-2 signal fluid circuit (at 100% duty cycle, the AFL fluid circuit is completely open).

The 3-2 signal fluid pressure moves the valve against the spring force. This action does not affect the transmission operating in Second gear.

Signal A fluid pressure exhausts and spring force moves the valve into the downshift position (second and third gear positions).

The 2nd clutch fluid pressure opens the valve and the line pressure feeds the converter clutch (CC) signal fluid circuit. The TCC signal fluid is orificed (#8) to the end of the CC signal valve and opposes the 2nd clutch fluid pressure. The TCC signal fluid is routed through a filter and orificed (#4) to the TCC solenoid.

Important: The orifice cup plug (#4) in the CC signal fluid circuit is smaller than the exhaust through the TCC solenoid. Therefore, fluid pressure does not build up at the end of the converter clutch apply valve.

Under normal operating conditions in second gear, the PCM keeps the normally open TCC solenoid de-energized (OFF). CC signal fluid exhausts through the open solenoid and spring force keeps the converter clutch apply valve in the release position.