Fifth Range

Fifth Range





Fifth Range Hydraulic Schematic

Before making a shift from fourth to fifth range, the Transmission Control Module (TCM) makes certain all of the Shift Valves are in the correct position with the Shift Valves C and E down and Shift Valve D up.

B Solenoid is de-energized, exhausting B trim valve signal pressure and the B Trim Valve moves up, which allows C1 clutch to exhaust through the Manual Selector Valve, Shift Valves E and C and the B Trim Valve.

A Trim Solenoid is de-energized, raising the A trim signal and A trim pressures. The A trim pressure is directed through Shift Valve D to C3 clutch, applying the clutch.

The TCM reduces the current to A Trim Solenoid, which controls the rate at which Trim Valve A supplies pressure to C3 clutch, and reduces the current to B Trim Solenoid, which controls the rate at which Trim Valve B exhausts C1 clutch, assuring a smooth transition from fourth to fifth range. C2 clutch continues to be applied by main pressure flowing through shift Valve E, Shift Valve D and the Manual Selector Valve.

The combination of C2 and C3 clutch application produces fifth range operation.

After the shift to fifth range is complete, the C Solenoid is de-energized, removing control main pressure from the top of Shift Valve C, causing the valve to move up and removing control main pressure from switch C. After the TCM has confirmed that Shift Valve C has moved up (pressure switch C turned off), B Solenoid is energized, directing pressure through Shift Valves E and D to the overdrive knockdown port of the main pressure regulator valve.

Overdrive knockdown reduces regulated main pressure. This function is calibration dependent and may not be active for all applications.

Pressure switches C and D are turned off, providing feedback that the C and D shift valves are in the up position, and pressure switch E remains on, providing feedback that shift valve E is in the down position.

If electrical power is interrupted with the transmission in fifth range, B Trim Solenoid, E Shift Solenoid, and F

Trim Solenoid, if the Torque Converter Clutch (TCC) is applied, de-energize. Although E Solenoid no longer supplies control main pressure to the top of Shift Valve E, control main pressure flows through Shift Valve C to the top of Shift Valve E, keeping the valve down The pressure from the B Trim Valve is exhausted. removing pressure from the overdrive knockdown circuit. allowing main pressure to regulate at a higher pressure Normally closed A Trim Solenoid continues to block the exhaust of the solenoid signal pressure (solenoid signal remains control main). The solenoid signal pressure on top of Trim Valve A produces maximum trim pressure, which is routed through Shift Valve D to C3 clutch. keeping the clutch applied. Main pressure feeds through Shift Valves E and D and the Manual Selector Valve to C2 clutch, keeping the clutch applied. The combination of C2 and C3 clutch application produces fifth range operation for limp home capability. If the TCC is applied, the F solenoid de-energizes, causing the F Trim valve to move up, exhausting pressure from the top of the Converter Flow Valve. The Converter Flow Valve moves up, redirecting main overage to converter in and converter out flow to the cooler. The TCC is now released.

If electrical power is interrupted with the transmission in fifth range (causing fifth range converter operation) and the Manual Selector Valve is moved to N (Neutral). C2 clutch exhausts through the Manual Selector Valve to exhaust backfill, releasing C2 clutch. C3 clutch remains applied. With only one clutch applied, the transmission goes to N (Neutral).

If electrical power is interrupted with the transmission in fifth range, (fifth range converter operation) and the Manual Selector Valve is moved to R (Reverse), C2 clutch exhausts through the Manual Selector Valve, releasing the clutch. C3 clutch remains applied. With only one clutch applied, the transmission goes to N (Neutral).

If electrical power is interrupted with the transmission in fifth range, resulting in only fifth and N (Neutral) operation, the engine may be shut down and restarted to attain N (Neutral), third and R (Reverse) operation.