When signal pressure is applied to the switch valve in listed Chrysler transmissions, the valve is shuttled to the full stroke position. In this position, the release circuit to the torque converter is vented and the apply circuit is opened to the line pressure. This moves the torque converter from the released or fluid coupling state to the lockup state. The apply pressure on the torque converter is equal to the full line pressure.
Chipped and/or performance enhanced transmissions can reach line pressures of 250+ psi. This level of pressure can potentially deform or balloon the torque converter. This deformation can affect fluid performance, efficiency and durability. Along with this, bore wear at TCC switch valve allows critical fluid loss that prevents proper TCC operation.
Reconditioning the bore and installing Sonnax oversized TCC apply limit switch valve kit 44912-41K limits the amount of pressure applied to the torque converter without affecting the line pressure and restores proper TCC operation.
The OEM calls this a TCC switch valve. The improved Sonnax version is called a TCC apply limit switch valve because, while it functions like the OE valve, it also limits the converter apply pressure.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.