Technically Speaking
- Subject: Extremely harsh 2-3 shift causing destruction of direct clutch
- Unit: Toyota U140 or 240 series
- Essential Reading: Rebuilder, Diagnostician
- Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor
Toyota vehicles using either the U140 or 240 series transmissions (see Figure 1) are known to produce a brutal 2-3 shift, to the point that the direct clutch disintegrates and spreads debris into the system, taking out the drum and cover (see Figure 2).
This is usually the reason the vehicle comes into the shop in the first place, and since road testing is out of the question you rebuild the unit without knowing what lies ahead. Sure enough, when it is road tested, the 2-3 shift is still so brutal that it can take out those clutches again, depending on how many times the 2-3 shift is allowed.
From the tech guys here at ATSG fielding these calls frequently, it has been determined that in just about every instance the computer will need to be replaced to resolve this issue. We have had rare instances in which either powering down the computer or reflashing it has tamed the shift to an acceptable feel.
David Chalker, ATSG technical consultant, dealt with a technician in one instance in which when the TPS was unplugged (see Figure 3), the shift pattern became fixed but the 2-3 shift brutality went away. We then had Pete Luban, ATSG technical supervisor, deal with a gentleman who actually monitored the shift-solenoid pattern to see what was occurring. Normally shift solenoid 1 is on for first, shift solenoid 2 turns on for second, shift solenoid 1 turns off for third and shift solenoid 2 turns off for fourth. When this malfunction on the 2-3 shift occurs, you will see shift solenoid 1 toggle rapidly from on to off several times, thus causing the brutal 2-3 shift.
When I received this call myself from John Parmenter, who was fighting this problem with an RAV4, I was able to tell him of these findings and he was able to get me these pictures for the article. Thanks, John! He also added that should you need to replace the cover, a Lexus cover will not interchange with the one for a Toyota. The internal area of the cover shown in Figure 4 will interfere with the feed pipes in the case, and the cover will not mount.
The computer is easy enough to get to, as you can see in figures 5, 6 and 7.
