The U151 and the U250 are five speed transaxles used from 2004-on in the Lexus ES300, ES330, RX330, RX350, and in many Toyota vehicles. The U250 is used behind the 2.4L 4 cylinder engine and the U151 is used behind the 3.0L, 3.3L, and 3.5L V-6 engines. The U151E and U250E are front wheel drive transaxles and the U151F is an all wheel drive transaxle.
Incorrectly identifying the solenoids in these units is a common problem. Three things we have learned for sure: getting them confused is easy, they can be installed in the wrong locations, and they sure don't work well when you do. When installed in the valve body, the four "long" or linear solenoids look almost identical. They have the same black, two terminal electrical connector, although I have seen some U250 valve bodies with a tan connector on the SLT solenoid. To make matters worse, the factory manual line drawings make it difficult to determine which solenoid goes where. To help identify its correct location, look at the valve area of the solenoid. Count the slots on the part of the solenoid that will live in the valve body bore when the solenoid is installed. There may be slots on both sides of the valve area, but for identification purposes, count the slots on the electrical connector side.
The four linear solenoids: SL1, SL2, SL3, and SLT are PWM solenoids. The ECM provides and controls both power and ground for each solenoid.
The other three solenoids: DSL, S4, and SR are on/off solenoids that are powered by the ECM and ground through the body of the solenoid.
Jeff Parlee is Director of Research and Development at Valve Body Xpress and a member of the Sonnax TASC Force® (Technical Automotive Specialties Committee), a group of recognized industry technical specialists, transmission rebuilders and Sonnax Industries Inc. technicians.
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