The direct clutch in Ford 5R55N transmissions is applied in Reverse, 4th and 5th Gear by the variable force PC-C solenoid. Fluid pressure from the solenoid is routed through the reverse modulator and reverse engagement valves, which then stroke appropriately to route apply pressure to the direct clutch. Wear at the reverse pressure modulator valve bore and end plug results in the leakage of the solenoid feed and direct clutch apply pressures, resulting in slipping or loss of 4th/5th Gear, burned direct clutch and delayed reverse engagement. Sonnax oversized reverse modulator valve kit 56947J-53K can restore proper hydraulic function and prevent future leakage.
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Vacuum test as indicated: