5L40E, A5S 360R, 4L40E, A4S 200R

Symptoms:

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

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

Correction:
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.

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 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

Kit Contains:

• Sleeve
• Valve
• Spring

SONNAX Installation Instructions