As the vehicle speed increases, TCM receives input signals from the two speed sensors, TP sensor, and other vehicle sensors to determine the precise moment to de-energize or turn OFF the 1-2 SS valve and to energize or turn ON the 4-5 SS valve.
Direct Clutch Apply
1-2 SS Valve: 1-2 SS valve is de-energized to prevent the feed limit fluid from flowing into 1-2 signal fluid passage and the 1-2 signal fluid pressure is drained through 1-2 SS valve.
3-4 Shift Valve: When the 1-2 signal fluid pressure drains through the 3-4 shift valve (345), the 3-4 shift valve spring (344) moves the valve to the released position. 345 fluid flows from 2-3 shift valve and flows directly into the direct clutch fluid circuit through 3-4 shift valve.
Direct Clutch: The direct Clutch fluid is sent to the direct clutch piston and applies the direct clutch plate to shift to 4th gear.
3-4 Shift Accumulator
Direct Clutch Accumulator: Direct clutch fluid is also sent to direct clutch accumulator assembly. Direct Clutch Fluid with accumulator spring tension to make the direct clutch accumulator piston overcome the accumulator fluid pressure to absorb the impact when direct clutch applies.
4-5 Shift Valve: After the first 3rd gear, 123 fluid feed the Coast Clutch. In 4th gear, the 4-5 shift valve (374) applies in preparation to shift to 5th gear. The operation makes the coast clutch feed fluid feeds the coast clutch fluid circuit, and 123 fluid drains.
TCC Release
TCC PWM Solenoid Valve: The filtered 2345 or reverse fluid remain in the TCC PWM solenoid valve. But according to shift pattern, TCM will remain the PWM solenoid OFF to prevent the filtered 2345 or Reverse fluid flowing into TCC signal fluid passage to keep the TCC released.
Fluid Pressure Directed in Preparation for 5th Gear
3-4 Shift Valve: 345 fluid is sent to 45 fluid circuit through 3-4 shift valve (345). #3 Ball Check Valve: 45 fluid goes against the #3 ball check valve and goes through the valve bore #27. The Valve Bore helps to control the overdrive clutch apply the 5th gear.
4-5 Shift Valve: 45 fluid is sent to 4-5 shift valve (374) and is prevented by the valve to be ready to upshift to 5th gear.
Overdrive Range, Fourth Gear - TCC Apply
