Title=Bold
Street Smart
U660E: Diagnosing
the Toyota 6-Speed by Mike Brown
members.atra.com
www.atra.com
Toyota’s
transmission
computer has
a learning
function
to adapt
transmission
performance
to vehicle
operation.
T he U660E first appeared
in the Lexus ES350 and
the Toyota Camry in 2007.
Then it showed up in the 2008
Avalon, followed by the Venza in
2009.
To diagnose and repair these
transmissions, you’ll need some
special tools. One tool you’ll want
to have is the techstream: Toyota’s
dedicated scan tool. But you don’t
have to buy the actual techstream:
Techstream lite is a PC-based ver-
sion of the scan tool, providing
you with the same access to the
Toyota/Scion/Lexus computer
system for a fraction of the cost.
Toyota’s transmission com-
puter has a learning function to
adapt transmission performance
to vehicle operation. So whether
you’re just replacing a solenoid or
the entire valve body, part of your
repair procedure should include
initializing the TCM and then road
testing the vehicle to give the
TCM a chance to relearn. Figure 1
36 GEARS August 2010
Figure 2
When performing a major repair, or park. • ECT
such as replacing the engine or trans- 2. Key off. • Utility
axle, or even the TCM, you’ll need to 3. Connect your techstream lite 7. A/T Code Reset.
reset the transaxle compensation code. connector to the diagnostic 8. Select Next to proceed.
This is Toyota’s term for reprogram- link connector (DLC3). 9. Select Exit.
ming the TCM. Naturally you’ll need to 4. Key on, engine off. 10. Perform road test to allow the
road test the vehicle to allow the TCM 5. Turn your computer on, and TCM to adapt to the transaxle
to relearn and adapt after resetting the enter the techstream lite pro- and conditions.
compensation code. gram.
To reset the transaxle compensa- 6. Enter the menu items in this Transaxle Compensation
tion code using techstream lite: order: Code (figure 1).
1. Move the shift lever to neutral • Powertrain Transaxle compensation codes are
GEARS August 2010 37
U660E: Diagnosing the Toyota 6-Speed
...most diagnostic
procedures only involve
inspecting one circuit
at a time. With a basic
understanding of the
system and a firm
grasp on the principles
of electricity, you
should have no trouble
performing accurate
diagnoses and repairs.
unique, 60-digit alphanumeric values
printed on the QR label on the trans-
axle. The code provides the computer
system with the initialization informa-
tion for that transaxle configuration.
Entering the wrong transaxle com-
pensation code into the TCM will cause
shift shock.
After you’ve installed the trans-
axle, the QR code label will be out of
position, where you can’t read it. So
always record the transaxle compensa-
tion code before installing the transaxle.
The chart (figure 2) shows you
which procedure will be necessary,
depending on which repairs you per-
formed.
Diagnostic Procedures
Toyota and Lexus use a large num-
ber of ECU-controlled systems. These
systems are often very intricate, requir-
ing a high level of technical knowledge
to troubleshoot.
But most diagnostic procedures
only involve inspecting one circuit at a Figure 3
time. With a basic understanding of the sending current to the faulty circuit. Check the solenoids for a short to
system and a firm grasp on the prin- At the same time, the TCM goes ground; connect your meter between
ciples of electricity, you should have no into failsafe operation, controlling the the each solenoid wire and the chassis
trouble performing accurate diagnoses remaining shift solenoids to provide ground. Resistance should be 10kΩ or
and repairs. basic transmission operation. higher. Below 10kΩ indicates a short
to ground.
Shift Solenoid Operation Inspection Procedure • If the solenoid resistance is
The TCM commands shifts by Remove the TCM from the trans- okay and there’s no indication of a short
turning the shift solenoids on or off in a axle and measure the solenoid resis- to ground, you’re probably dealing with
specific sequence. tances. (figure 3) a faulty TCM.
When there’s an open or short SLT, SLU, SL1, SL2, SL3, and • If the solenoid resistance is out
circuit in any shift solenoid circuit, the SL4................................ 5.0–5.6Ω of spec, or the resistance between the
TCM detects the problem, lights the SL.................................... 11–15Ω solenoid and ground is below 10kΩ,
MIL, and stores a code. It also stops you’ll need to replace the solenoid.
38 GEARS August 2010
U660E: Diagnosing the Toyota 6-Speed
Replacing the ATF
The U660E has a special ATF fill-
ing procedure to improve the accuracy
of the ATF level after repairs (figures
4&5).
Because of this, the oil filler tube
and oil level gauge used in convention-
al automatic transmissions have been
discontinued, eliminating the need to
inspect the fluid level as part of routine
maintenance.
That’s going to wrap it up for now.
Keep your eyes open for more about
the U660E as we keep these transmis-
sions street smart.
Figure 4
Figure 5
40 GEARS August 2010
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