Third Range

Third Range
Before making the shift from second to third range, the transmission control module (TCM) makes certain all of the shift valves are in the correct position with the C, D and E shift valves up.

Pressure control solenoid B is de-energized, exhausting trim signal pressure which allows trim valve B to move up, exhausting the 2nd clutch. Pressure control solenoid A is de-energized, raising the A trim signal and A trim pressures. The A trim pressure is directed through shift solenoid D shift valve to the 3rd, 5th, and Reverse clutch. The TCM reduces current to pressure control solenoid A, which controls the rate at which trim valve A supplies pressure to the 3rd, 5th, and Reverse clutch, and reduces current to shift solenoid B, which controls the rate at which trim valve B exhausts the 2nd clutch, assuring a smooth transition to third range. Main pressure continues to flow through the E shift valve and manual valve to the 1-2-3-4 clutch, keeping the clutch applied.

The combination of the 1-2-3-4 clutch and the 3rd, 5th, and Reverse clutch application produces third range operation.

After the shift into third range is complete, shift solenoid C is energized and directs control main pressure to the top of the C shift valve, pushing the valve down. With shift valve C in the downward position, the 2nd clutch feed is exhausted through the C shift valve to exhaust backfill keeping the 2nd clutch released and the 4-5 clutch has an exhaust path through the C shift valve to the B trim valve, keeping the 4-5 clutch released.

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

If electrical power is interrupted with the transmission in third range, Solenoid C and the torque converter clutch pulse width modulated (TCC PWM) solenoid, if TCC is applied, is de-energized. Shift valve C will move up, changing the exhaust path of the 4-5 clutch to exhaust backfill and the exhaust path of the 2nd clutch to the B trim valve. Normally closed pressure control solenoid A continues to block the exhaust of the A trim signal pressure, and trim signal remains control main. The solenoid signal pressure on top of trim valve A produces maximum A trim pressure, which is routed through shift valve D to the 3rd, 5th, and Reverse clutch, keeping the clutch applied. With the manual selector in a forward position, main pressure continues to feed the 1-2-3-4 clutch through the E shift valve and manual valve. The combination of the 1-2-3-4 clutch and the 3rd, 5th, and Reverse clutch applied keeps the transmission in third range for limp home capability. If the TCC is applied, the TCC PWM solenoid de-energizes, causing the TCC PWM 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 to the cooler. The TCC is now released.

If electrical power is interrupted with the transmission in third range, and the manual valve is moved to Neutral (N), the 1-2-3-4 clutch will exhaust through the manual valve to exhaust backfill. The 3rd, 5th, and Reverse clutch remains applied. With only one clutch applied, the transmission goes to Neutral (N).

If electrical power is interrupted with the transmission in third range and the manual valve is moved to the Reverse (R) position, the 1-2-3-4 clutch exhausts through the manual valve which releases the clutch. Main pressure goes through shift valve E, the manual valve and shift valve D to low and Reverse clutch, applying the clutch. The combination of the 3rd, 5th, and Reverse clutch and the low and Reverse clutch application produces Reverse (R) range for limp home capability.





Third Range