TASC Force Tips
- Author: Jeff Parlee
The U151 and U250 are five-speed transaxles that are used in the Lexus ES300, ES330, RX330 and RX350 as well as many Toyota vehicles from 2004 on. The U250 is used behind the 2.4-liter four-cylinder engine, and the U151 is used behind the 3.0-, 3.3- and 3.5-liter V-6 engines. The U151E and the 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, you can install them 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.
SL1 has two slots on the electrical-connector side and three slots on the opposite side. Resistance at 68°F should be 5-5.6 ohms. SL1 is a clutch-control solenoid and is also known as pressure-control solenoid A.
SL2 and SL3 each have four slots on the electrical-connector side and one slot on the opposite side. Resistance at 68°F should be 5-5.6 ohms. SL2 and SL3 are clutch-control solenoids.
SL2 is also known as pressure-control solenoid B. SL3 is also known as pressure-control solenoid C. These two solenoids do look the same, but interchanging them successfully has not been verified. Mark them and reinstall them in their original positions.
SLT has five slots on the electrical-connector side and none on the opposite side. Resistance at 68°F should be 5-5.6 ohms. SLT controls line-pressure rise and is also known as pressure-control solenoid D.
The other three solenoids – DSL, S4 and SR – are on/off solenoids that are powered by the ECM and grounded through the body of the solenoid.
DSL controls the lockup clutch in the torque converter. It has a single-wire reddish/brown electrical connector, and the hold-down bracket is part of the solenoid. Resistance at 68°F should be 11-13 ohms. DSL is also known as the TCC solenoid.
S4 is a shift solenoid with a single-wire black connector, and the hold-down bracket is part of the solenoid. Resistance at 68°F should be 11-15 ohms. S4 is also known as shift solenoid D.
SR has a black electrical connector, and the hold-down bracket is part of the solenoid. Resistance at 68°F should be 11-15 ohms. SR is also known as shift solenoid E.
Jeff Parlee is director of product support at ValveBody 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.
