Power Off High Default

Power Off High Default

If the transmission is in Third or Fourth gear during a transmission electrical component malfunction, the transmission will default 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.

Variable Hi and 2-3-4 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.

Shift Solenoid 1

The shift solenoid 1 defaults to its normally closed state (OFF), allowing solenoid 1 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 VH 234 clutch/B cooling feed fluid pressure to continue to feed the VH 234 clutch circuit.

Variable Hi and 2-3-4 Clutch Assembly

VH 234 clutch fluid is directed to the variable hi and 2-3-4 clutch piston to apply the variable hi and 2-3-4 clutch plates.

Shift Accumulation

Variable Hi and 2-3-4 Clutch Accumulator

VH 234 clutch fluid is also sent to the variable hi and 2-3-4 clutch accumulator assembly. VH 234 clutch fluid moves the variable hi and 2-3-4 clutch accumulator piston against accumulator spring force to cushion the apply of the variable hi and 2-3-4 clutch assembly.

1-3 Reverse Clutch Releases

If the transmission is operating in Third 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.

4th Clutch Releases

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

Power Off High Default