September 30, 2005
Ford 4R100 PWM units use a plunger valve assembly and coil spring to cushion the TCC control valve. That assembly uses regulated converter pressure as a variable hydraulic spring to control the rate of TCC apply. Continuous oscillation of the TCC control plunger valve wears the sleeve I.D., allowing regulated converter pressure leakage. This can result in premature or bumpy TCC apply and/or shudder. Sonnax TCC control plunger valve kit 36424-08K restores hydrualic integrity.
Use of the Sonnax kit does not convert hydraulics to On-Off for use with single piston conversion. The PWM control is a function of the computer and TCC/PWM solenoid.