4-5-6 Clutch Applies or Remains Applied
R1/4-5-6 Pressure Control (PC) Solenoid
The R1/4-5-6 PC solenoid defaults to its normally-high state (ON), allowing actuator feed limit fluid to enter the PCS R1/4-5-6 clutch fluid circuit. PCS R1/4-5-6 clutch fluid is routed through orifice #11 to the R1/4-5-6 clutch regulator valve, and through orifice #34 to the R1/4-5-6 clutch boost valve. If the transmission is operating in First, Second or Third gear when an electrical malfunction occurs, the 4-5-6 clutch will apply. If the transmission is operating in Fourth, Fifth or Sixth gear when the electrical malfunction occurs, the 4-5-6 clutch remains applied.
R1/4-5-6 Clutch Boost Valve
PCS R1/4-5-6 clutch fluid pressure acts on a differential area, moving the R1/4-5-6 clutch boost valve against R1/4-5-6 clutch boost valve spring force, to block R1/4-5-6 clutch feed fluid from entering the R1/4-5-6 clutch feedback circuit, and opening the R1/4-5-6 clutch feedback circuit to exhaust backfill. This results in the R1/4-5-6 clutch regulator valve moving to the full feed position, sending full R1/4-5-6 clutch feed pressure (full line pressure) to the 4-5-6 clutch.
R1/4-5-6 Clutch Regulator Valve
PCS R1/4-5-6 clutch fluid moves the R1/4-5-6 clutch regulator valve, against R1/4-5-6 clutch regulator valve spring force, to the applied position. This allows line fluid pressure to pass through the valve into the R1/4-5-6 clutch feed circuit. R1/4-5-6 clutch feed fluid is then routed to the clutch select valve, the R1/4-5-6 clutch boost valve, and through orifices #9 and #12 to the spring end of the R1/4-5-6 clutch regulator valve. When the R1/4-5-6 clutch regulator valve is in this position, latch fluid exhausts through the valve allowing 4-5-6 clutch fluid to shuttle the #1 ball check valve.
#1 Ball Check Valve
Orificed 4-5-6 clutch fluid pressure seats the #1 ball check valve against the exhausting latch fluid passage. 4-5-6 clutch fluid is then directed into the latch circuit to replace the exhausting latch pressure and is routed to the clutch select valve. Latch fluid combines with clutch select valve spring force and holds the valve in this position during all six forward gear ranges.
Clutch Select Valve
R1/4-5-6 clutch feed fluid passes through the clutch select valve and enters the 4-5-6 clutch circuit. 4-5-6 clutch fluid is routed to the 4-5-6 clutch assembly, and through orifice #2 to the #1 ball check valve.
4-5-6 Clutch
4-5-6 clutch fluid enters the 3-5-reverse and 4-5-6 clutch housing assembly, and moves the 4-5-6 clutch piston against spring force and exhaust backfill pressure to apply the 4-5-6 clutch plates.
Accumulator
PCS R1/4-5-6 clutch fluid is also routed to an accumulator valve. The accumulator valve is used to dampen any pressure irregularities occurring in the PCS R1/4-5-6 clutch fluid circuit. This helps to control clutch apply fluid pressure and clutch apply feel.