Operation CHARM: Car repair manuals for everyone.

First Gear




Drive Range, First Gear

When the gear selector lever is moved to the Drive Range (D) position from the Neutral (N) position, after the first 1-2 shift has occurred, the following changes occur to shift the transmission into Drive Range - First Gear.

1-3 Reverse Clutch Applies

Pressure Control (PC) Solenoid 4 Trim

The PC solenoid 4 trim is energized (ON) allowing actuator feed limit fluid to enter the PCS 4 signal circuit. PCS 4 signal fluid is then routed through orifice 18 to the 1-3 reverse clutch regulator valve.

Shift Solenoid 2

The shift solenoid 2 is energized, allowing actuator feed limit fluid to enter the solenoid 2 signal fluid circuit. Solenoid 2 signal fluid is routed to the shift solenoid valve - mode A. Solenoid 2 signal fluid is also routed to the variable hi and 2-3-4 clutch regulator valve where it enters the PS3 fluid circuit, and to the 1-3 reverse clutch regulator valve where it enters the PS1 fluid circuit.

1-3 Reverse Clutch Regulator Valve

PCS 4 signal fluid, at the 1-3 reverse clutch regulator valve, opposes 1-3 reverse clutch regulator valve spring force and 13 reverse clutch feedback fluid pressure to regulate line or auxiliary line pressure into the 13 reverse clutch/A cooling feed circuit.

#3 Ball Check Valve

13 reverse clutch feedback fluid unseats the #3 ball check valve, allowing excess pressure to pass into the actuator feed limit circuit. This helps to control clutch apply fluid pressure and clutch apply feel.

Shift Solenoid Valve - Mode A

Solenoid 2 signal fluid is routed to the shift solenoid valve - mode A and moves the valve against shift solenoid valve - mode A spring force to the applied position. This allows 13 reverse clutch/A cooling feed fluid to enter the 13 reverse clutch circuit.

1-3 Reverse Clutch Assembly

13 reverse clutch fluid enters the transmission fluid pump cover and moves the 1-3 reverse clutch piston against spring force to apply the 1-3 reverse clutch plates.

#3 Pressure Switch

Solenoid 2 signal fluid passes through the variable hi and 2-3-4 clutch regulator valve into the PS3 fluid passage. PS3 fluid opens the normally closed #3 pressure switch, signaling the TCM that the transmission is in Drive Range - First Gear.

#1 Pressure Switch

Solenoid 2 signal fluid passes through the 1-3 reverse clutch regulator valve into the PS1 fluid passage. PS1 fluid opens the normally closed #1 pressure switch, signaling the TCM that the transmission is in Drive Range - First Gear.

Shift Accumulation

1-3 Reverse Clutch Accumulator

13 reverse clutch fluid is also sent to the 1-3 reverse clutch accumulator assembly. 13 reverse clutch fluid moves the 1-3 reverse clutch accumulator piston against accumulator spring force to cushion the apply of the 1-3 reverse clutch assembly.

Drive Range, First Gear