On occasions, solenoids that appear to be similar may be mistaken as identical. Toyota’s U150 series transmission is a good example of this (Figure 1). This valve body contains seven solenoids of which four look very similar (Figure 2). They all have the same type of electrical connection both in configuration and color (early style color). The snouts are also the same in diameter and length. And they all have the same design retaining bracket slots.
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Yet when these solenoids are laid side by side for comparison, one can easily see the SL1 solenoid is very different than the others. The SL2 and the SL3 are the same and the SLT is similar yet still very different. The SLT and the SL3 solenoid are installed into the valve body correctly as seen in Figure 3, but can be easily swapped and installed incorrectly (Figure 4).
This would cause two problems. With the SL3 solenoid in the SLT location, a slight boost in pressure may be seen due to the manual valve routing pressure to the boost valve, but there will be no line pressure rise with throttle opening. The SLT solenoid being in the SL3 location prevents the proper operation of the C1 Clutch Control Valve prohibiting a forward engagement. In short, no forward and a slipping reverse backing up a slight grade when these two solenoids are accidently swapped.
Some 2005 - 2007 Toyota Camry's equipped with the 2AZ-FE engine and U250 transaxle may exhibit a harsh 5-4 downshift after driving at speeds above 45mph and decelerating to 28 mph. Toyota TSB numbers, TC013-05 and TC010-06. One cause can be due to pressure instability problems with the SLT Solenoid (Line Pressure Control Solenoid) requiring replacement.
The new design SLT solenoid has a brown connector (Figure 5). Beware; there are new design SLT solenoids with a black connector allowing for the same incorrect placement of the solenoid. To know if you have the newer style SLT solenoid, the screw cap at the tip of the solenoid has a slot for a flat blade screwdriver as opposed to an Allen/hex wrench pocket.
For your reference, this is Toyota part No. 35290-45010