Third Range: Notes

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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 shift valve 1, shift valve 2, and shift valve 3 de-stroked.

Pressure control solenoid 2 (PCS2) is de-energized, exhausting PCS2 signal pressure which allows the pressure control valve 2 to de-stroke, exhausting the 2-6 clutch. PCS1 is de-energized, raising PCS1 signal and PCS1 pressures. The PCS1 pressure is directed through shift valve 2 to the 3rd, 5th, and reverse clutch. The TCM reduces current to PCS1, which controls the rate at which the pressure control valve 1 supplies pressure to the 3rd, 5th, and reverse clutch, and reduces current to PCS2, which controls the rate at which pressure control valve 2 exhausts the 2-6 clutch, assuring a smooth transition to third range. Main pressure continues to flow through shift solenoid 3 (SS3) and the manual selector 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, SS1 is energized and directs control main pressure to the top of shift valve 1, stroking the valve. With shift valve 1 in the stroked position, the 2-6 clutch feed is exhausted through shift valve 1 to exhaust backfill keeping the 2-6 clutch released and the 4-5-6 clutch has an exhaust path through shift valve 1 to pressure control valve 2, keeping the 4-5-6 clutch released.

Pressure switch 1 turns ON, providing feedback that shift valve 1 is stroked. Pressure switch 2 and pressure switch 3 remain OFF, providing feedback that shift valve 2 and shift valve 3 are in the de-stroked position.

If electrical power is interrupted while the transmission is in third range, SS1 and the torque converter clutch (TCC) solenoid (if TCC is applied) are de-energized. Shift valve 1 de-strokes, changing the exhaust path of the 4-5-6 clutch to exhaust backfill and the exhaust path of the 2-6 clutch to pressure control valve 2. Normally closed PCS1 continues to block the exhaust of the PCS1 signal pressure (signal remains control main). The signal pressure on top of pressure control valve 1 produces maximum PCS1 pressure, which is routed through shift valve 2 to the 3rd, 5th, and reverse clutch, keeping the clutch applied. With the manual selector valve in a forward position, main pressure continues to feed the 1-2-3-4 clutch through shift valve 3 and the manual selector 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 solenoid de-energizes, causing the TCC valve to de-stroke, exhausting pressure from the top of the converter flow valve. The converter flow valve de-strokes, redirecting main overage to converter in and converter out to the cooler. The TCC is now released.

If electrical power is interrupted while the transmission is in third range, and the manual selector valve is moved to Neutral (N), the 1-2-3-4 clutch exhausts through the manual selector 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 while the transmission is in third range and the manual selector valve is moved to the Reverse (R) position, the 1-2-3-4 clutch exhausts through the manual selector valve which releases the clutch. Main pressure goes through shift valve 3, the manual selector valve and shift valve 2 to the 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.