Clutch Control Valves

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

The A, B, C, and F clutch control valves regulate line pressure for smooth clutch application. The clutch control valve design includes a slightly smaller land at the right end of the valve. The adjacent different diameter lands creates a differential chamber. Fluid under pressure in this chamber applies more force to the larger diameter land than to the smaller diameter land.

The clutch control valve moves to open or close a passage between line pressure and the clutch control circuit. With the valve at the left of the bore, the passage between line pressure and X clutch control is restricted (closed) and the clutch is released. With the valve at the right of the bore, the passage between line pressure and X clutch control is not restricted (open) and the clutch is applied.
The clutch control valve is positioned in the bore by balancing two opposing forces. On the left side of the valve is the shift solenoid that pushes the valve to the right, thereby opening the passage and increasing pressure in the clutch control circuit.
Clutch control pressure in the differential chamber applies more force to the land on the left pushing the valve towards the solenoid, thereby lowering pressure in the clutch control circuit.
When the shift solenoid is de-energized, the weight of the fluid in the elevated exhaust circuit acts on the clutch control valve to keep it positioned against the solenoid pintle. The passage from line pressure to X clutch control is closed.
To apply the clutch, the TCM or PCM applies current to the shift solenoid and hydraulic pressure in the X clutch control circuit increases proportionally.
As the solenoid force increases, the clutch control valve moves and connects line pressure to X clutch control.
X clutch control fluid begins to fill the clutch. X clutch control also acts on the clutch control valve via the differential chamber.
The clutch control valve cycles rapidly as the X clutch control pressure increases and the clutch applies.

The D and E clutch control valves regulate line pressure for smooth clutch application. The clutch control valve design is similar to the A, B, C, and F clutch control valves, except there are 2 progressively smaller diameter lands at the right end of the valve. The different diameter lands create two differential chambers. Valve operation is identical to the other clutch control valves except the D and E clutch control valves can use 2 different forces to balance the valve against the solenoid. Under low load conditions, the X clutch control circuit feeds both differential chambers resulting more force acting against the solenoid. The clutch control valve is positioned close to the solenoid and about 689 kPa (100 psi) of regulated line pressure applies or holds the clutch. Under high load conditions, the X clutch control circuit feeds only 1 differential chamber resulting in less force acting against the solenoid. The clutch control valve is positioned further away from the solenoid and about 1, 379 kPa (200 psi) of regulated line pressure applies or holds the clutch.