The TCC control valve in Allison^® 1000/2000/2400 transmissions is controlled by a PWM solenoid that continuously oscillates the valve. When the bore becomes worn from constant motion, a loss of converter apply pressure can occur. This can cause issues like no lockup, converter and TCC shudder and TCC slip. Reconditioning the bore and installing Sonnax oversized TCC control valve kit 37000-37K restores TCC function to normal operation. Valve is hardcoat anodized to protect against premature wear.