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  • Erratic TCC apply pressure
  • Excess TCC slip
  • Harsh TCC apply & release
  • Low cooler & lube pressure
  • TCC codes


Excess bore wear at the secondary pressure regulator valve allows critical pressure loss and/or valve hang-up.


Recover hydraulic control and revive TCC/lube/cooler pressures by reconditioning the bore and installing Sonnax oversized secondary pressure regulator valve kit.

U341E, U341F

Oversized Secondary Pressure Regulator Valve Kit
Part No. 37740-07K

You need this if... View Instructions

Vehicles with Toyota/Lexus U341E and U341F transmissions commonly have TCC problems such as harsh apply and release or excess slip, often accompanied by TCC codes. These issues can be caused by bore wear at the secondary pressure regulator valve, which allows vital fluid to escape the circuit. In addition, cooler and lube pressures can be negatively affected, resulting in overheating and lube failures. Reconditioning the bore and installing Sonnax oversized secondary pressure regulator valve kit 37740-07K restores critical clearances for renewed TCC, cooler and lube operation.

  • Lengthened critical spool for added stability and wear prevention
  • Hardcoat anodized aluminum valve combats premature wear
  • Valve
  • End Plug

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.

Toyota U341E/F Valve Body Layout

Toyotau341ef vbl thumb

September 30, 2005

Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits

Gregg Nader

Topics: Diagnostics And Theory Transmission

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  • 37740 07k combo
  • 37740 07k

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

  • 37740 07k test