Chevrolet Sonic Repair Manual: Drive Range, First Gear (Gen 1)

As the vehicle speed increases, the transmission control module (TCM) receives input signals from the automatic transmission input and output speed sensors, throttle position sensor and other vehicle sensors to determine the precise moment to deenergize or ?urn OFF?the shift solenoid, and to command OFF the normally-high R1/456 pressure control solenoid 3.

Low & Reverse Clutch Releases

Shift Solenoid

The shift solenoid is ?ommanded OFF?allowing shift solenoid fluid pressure to exhaust from the clutch select valve and the TCC regulator apply valve.

Clutch Select Valve

Shift solenoid fluid is exhausted from the clutch select valve and clutch select valve spring force moves the valve to the released position. This allows R1 fluid pressure to pass through the valve into the exhaust backfill circuit where it exhausts. Drive fluid from the manual valve passes through the clutch select valve and enters the drive 1-6 fluid circuit. Drive 1-6 fluid is routed to the R1/456 clutch regulator valve, the 35 reverse clutch regulator valve, and the TCC regulator valve.

Low and Reverse Clutch

Low and reverse clutch spring force moves the low and reverse clutch piston to release the low and reverse clutch plates and force R1 fluid to exhaust from the case assembly. The exhausting R1 fluid is routed to the clutch select valve where it enters the exhaust backfill circuit.

Fluid Pressure Directed in Preparation for a Shift

R1/456 Pressure Control (PC) Solenoid 3

The R1/456 PC solenoid 3 is commanded OFF allowing PCS R1/456 clutch fluid to exhaust from the R1/456 clutch regulator valve.

R1/456 Clutch Regulator Valve

R1/456 clutch regulator valve spring force moves the valve to the released position, allowing R1/456 clutch feed fluid to enter the exhaust backfill circuit, and drive 1-6 fluid to enter the PS4 fluid circuit. PS4 fluid is then routed to the normally-closed #4 pressure switch and opens the switch. PS4 fluid is also routed to the #1 ball check valve and flows into the CSV2 latch fluid circuit.

#1 Ball Check Valve

PS4 fluid pressure seats the #1 ball check valve against the 456 clutch fluid circuit. PS4 fluid is then directed into the CSV2 latch circuit and routed to the clutch select valve. CSV2 latch fluid combines with clutch select valve spring force and holds the valve in this position during all six forward gear ranges.

#2 Ball Check Valve

Drive 1-6 fluid pressure seats the #2 ball check valve against the 35 reverse clutch feed fluid passage, and is directed into the 35 reverse clutch feed/drive 1-6 circuit. 35 reverse clutch feed/drive 1-6 fluid is routed through orifice #25 to the 35 Reverse clutch regulator valve.

3-5-Reverse Clutch Regulator Valve

35 reverse clutch feed/drive 1-6 fluid passes through the 3- 5-reverse clutch regulator valve into the PS3 fluid circuit. PS3 fluid is then routed to the normally-closed #3 pressure switch and opens the switch.

Fluid Pressure Directed in Preparation for Torque Converter Clutch (TCC) Apply

TCC Regulator Apply Valve

Drive 1-6 fluid is routed to the TCC regulator apply valve in preparation for TCC apply.

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