Hybrid Low, 1-2 Clutch Remains Applied

WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.

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.

Hybrid Low, 1-2 Clutch Boost Valve

PCS 3 signal fluid pressure acts on a differential area of the hybrid low, 1-2 clutch boost valve, moving the valve against hybrid low, 1-2 clutch boost valve spring force to block HL 12 clutch/4th clutch feed fluid from entering the HL 12 clutch/4th clutch feedback circuit, and opening the HL 12 clutch/4th clutch feedback circuit to exhaust. This results in the hybrid low, 1-2 clutch regulator valve moving to the full feed position, sending full HL 12 clutch/4th clutch feed pressure (full line pressure) to the hybrid low, 1-2 clutch.

Hybrid Low, 1-2 Clutch Regulator Valve

PCS 3 signal fluid moves the hybrid low, 1-2 clutch regulator valve, against hybrid low, 1-2 clutch regulator valve spring force, to the applied position. This allows line or auxiliary line fluid to pass through the valve into the HL 12 clutch/4th clutch feed circuit.

Shift Solenoid Valve - Mode B

HL 12 clutch/4th clutch feed fluid is routed to the shift solenoid valve - mode B, where it passes through the valve into the HL 12 clutch circuit.

Hybrid Low, 1-2 Clutch Assembly

HL 12 clutch fluid pressure enters the rear case assembly behind the hybrid low, 1-2 clutch piston and moves the piston against spring force to apply the hybrid low, 1-2 clutch plates.

1-3 Clutch Releases

If the transmission is operating in First 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, Second Gear for a complete description of 1-3 clutch release.