If the transmission is in Third or Fourth gear during a transmission electrical component malfunction, the transmission will defualt to high. All solenoids will default to their normal state. The transmission will remain in Power Off High Default until the ignition has been turned off, or the transmission is shifted to Reverse (R). When the vehicle is restarted, and shifted back into Drive (D), the transmission will then operate in Power Off Low Default. This default action enables the vehicle to be safely driven to a service center.

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 #34 to the hybrid low, 1-2 clutch regulator valve; through orifice #33 to the hybrid low, 1-2 clutch boost valve; and to the shift solenoid valve - mode B.

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 B.

Shift Solenoid Valve - Mode B

PCS 3 signal fluid pressure acts on a differential area of the shift solenoid valve - mode B, holding the valve in the applied position against shift solenoid valve - mode B spring force. This allows HD 234 clutch/B cooling feed fluid pressure to continue to feed the HD 234 clutch circuit.

Hybrid Direct, 2-3-4 Clutch Assembly

HD 234 clutch fluid is directed to the hybrid direct, 2-3-4 clutch piston to apply the hybrid direct, 2-3-4 clutch plates.

If the transmission is operating in Third gear when an electrical malfunction occurs, the normally closed shift solenoid 1 and the normally low pressure control solenoid 4 trim default to their normal states (OFF) and the 1-3 clutch is released. Refer to Drive Range - Fourth Gear for a complete discription of 1-3 clutch release.

If the tranmission is operating in Fourth gear when an electrical malfunction occurs, the shift solenoid 1 defaults to its normally closed state (OFF) and the 4th clutch is released. Refer to EVT Mode High - From Drive Range 4th Gear for a complete description of 4th clutch release.