Power Off Low Default

Power Off Low Default

If the transmission is in Drive - Series Mode 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 clutch regulator valve; through orifice #12 to the variable low and 1-2 reverse clutch boost valve; and to the shift solenoid valve -mode B.

Variable Low and 1-2 Reverse Clutch Boost Valve

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

Variable Low and 1-2 Reverse Clutch Regulator Valve

PCS 3 signal fluid moves the variable low and 1-2 reverse clutch regulator valve, against variable low and 1-2 reverse 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 clutch feed circuit.

Shift Solenoid Valve - Mode B

VL 12 reverse 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

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. See Neutral for a complete description of 1-3 reverse clutch release.

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