• No Reverse
  • TCC lining overheat
  • Burnt Low/Reverse clutch
  • Burnt Reverse clutch


Wear at the Reverse lockout valve can allow TCC signal and Reverse oil to cross-leak or leak to exhaust.


Reverse lockout valve kit includes a wear-resistant sleeve, modified valve and spring to establish proper pressure and prevent leakage of TCC signal or Reverse oil at the worn bore.

5L40-E, 5L50-E

Reverse Lockout Valve Kit
Part No. 55211-11K

You need this if... View Instructions Find a Distributor

When GM 5L40-E and 5L50-E units are in Reverse gear, the Reverse lockout valve directs reverse fluid into the Reverse lockout fluid (RLO) circuit to apply the Reverse clutch and Low/Reverse clutch. Wear at the inboard spool bore can allow Reverse fluid pressure to enter the TCC signal circuit and partially stroke the TCC regulator valve. This can result in TCC overheat and loss of Reverse. The Reverse lockout valve also responds to TCC signal fluid pressure to block fluid from entering the Reverse lockout circuit, thus preventing the Reverse clutch and low/reverse clutch from applying while the vehicle is moving forward. If there is excessive bore leakage, TCC signal can cross leak into the RLO circuit, and begin to apply and burn the Reverse clutches or cause transmission damage. Sonnax Reverse lockout valve kit 55211-11K eliminates bore wear, and re-establishes the correct hydraulic pressures to prevent these problems.

  • Highly wear-resistant sleeve provides significantly more valve support to reduce leakage and prevent wear
  • Hardcoat anodized aluminum valve combats premature wear
  • Tool kit F-55211-TL can also be used for valve kit 55211-01K
  • Valve
  • Sleeve
  • Spring

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

GM 5L40-E, 5L50-E Valve Body Layout

GM 5L40-E, 5L50-E Valve Body Layout
  • 5L40-E, 5L50-E Reverse Lockout Valve Kit 55211-11K
  • 5L40-E, 5L50-E Reverse Lockout Valve Kit 55211-11K

You need this if...

5L40-E, 5L50-E Reverse Lockout Valve Kit Vacuum Test Locations