Power Off Low Default

Power Off Low Default

If the transmission is in First or Second gear during a transmission electrical component malfunction, the transmission will default to Low. All solenoids will default to their normal state. This default action enables the vehicle to be safely driven to a service center.

Variable Low and 1-2 Reverse Clutch Remains Applied

Pressure Control (PC) Solenoid 3 Trim

The PC solenoid 3 trim defaults to its normally high state (ON) allowing actuator feed limit fluid to enter the PCS 3 signal circuit. PCS 3 signal fluid is then routed through orifice #30 to the variable low and 1-2 reverse and 4th clutch regulator valve; through orifice 12 to the variable low and 1-2 reverse and 4th clutch boost valve; and to the shift solenoid valve - mode B.

Variable Low and 1-2 Reverse and 4th Clutch Boost Valve

PCS 3 signal fluid pressure acts on a differential area of the variable low and 1-2 reverse and 4th clutch boost valve, moving the valve against variable low and 1-2 reverse and 4th clutch boost valve spring force to block VL 12 reverse/4th clutch feed fluid from entering the VL 12 reverse/4th clutch feedback circuit, and opening the VL 12 reverse/4th clutch feedback circuit to exhaust. This results in the variable low and 1-2 reverse and 4th clutch regulator valve moving to the full feed position, sending full VL 12 reverse/4th clutch feed pressure (full line pressure) to the variable low and 1-2 reverse clutch.

Variable Low and 1-2 Reverse and 4th Clutch Regulator Valve

PCS 3 signal fluid moves the variable low and 1-2 reverse and 4th clutch regulator valve, against variable low and 1-2 reverse and 4th clutch regulator valve spring force, to the applied position. This allows line or auxiliary line fluid to pass through the valve into the VL 12 reverse/4th clutch feed circuit.

Shift Solenoid Valve - Mode B

VL 12 reverse/4th clutch feed fluid is routed to the shift solenoid valve - mode B, where it passes through the valve into the VL 12 reverse clutch circuit.

Variable Low and 1-2 Reverse Clutch Assembly

VL 12 reverse clutch fluid pressure enters the case assembly behind the variable low and 1-2 reverse clutch piston and moves the piston against spring force to apply the variable low and 1-2 reverse clutch plates.

1-3 Reverse Clutch Releases

If the transmission is operating in First gear when an electrical malfunction occurs, the normally closed shift solenoid 2 and the normally low pressure control solenoid 4 trim default to their normal states (OFF) and the 1-3 reverse clutch is released.

Variable Hi and 2-3-4 Clutch Releases

If the transmission is operating in Second gear when an electrical malfunction occurs, the shift solenoid 2 defaults to its normally closed state (OFF) and the variable hi and 2-3-4 clutch is released.

Shift Solenoid 2

The shift solenoid 2 defaults to its normally closed state (OFF), allowing solenoid 2 signal fluid to exhaust from the shift solenoid valve - mode A, the variable hi and 2-3-4 clutch regulator valve, and the 1-3 reverse clutch regulator valve.

Variable Hi and 2-3-4 Clutch Assembly

VH 234 clutch fluid pressure is exhausted from the case assembly, allowing variable hi and 2-3-4 clutch spring force to move the variable hi and 2-3-4 clutch piston and release the variable hi and 2-3-4 clutch plates.

Shift Solenoid Valve - Mode B

Exhausting VH 234 clutch fluid pressure passes through the shift solenoid valve - mode B into the 234 clutch feed circuit.

Shift Solenoid Valve - Mode A

Shift solenoid valve - mode A spring force moves the shift solenoid valve - mode A to the released position, allowing 234 clutch feed fluid pressure to exhaust through the valve.

Shift Accumulation

Variable Low and 1-2 Reverse Clutch Accumulator

VL 12 reverse clutch fluid is also sent to the variable low and 1-2 reverse clutch accumulator assembly. VL 12 reverse clutch fluid moves the variable low and 1-2 reverse clutch accumulator piston against accumulator spring force to cushion the apply of the variable low and reverse clutch assembly.

1-3 Reverse Clutch Accumulator

13 reverse clutch fluid also exhausts from the 1-3 reverse clutch accumulator assembly. Accumulator spring force moves the 1-3 reverse clutch accumulator piston to the released position.

Power Off Low Default