The ATRA Tech HotLine still receives calls on Toyota/Lexus U140/U240 and U150/U250 transmissions with shifting issues. These vehicles exhibit a number of conditions, including slipping or binding shifts.
Often these problem transmissions have already been rebuilt, with new gaskets, seals, O-rings, and sometimes new solenoids. But they still have problems: That’s usually when we get the call.
The most common issues we hear about on U140/U240 are long, drawn-out, or flare 2-3 shifts, or a 2-3 flare with a bindup at the end of the shift. Sometimes there are even long, drawn-out, slipping 1-2 shifts. The U150/U250 complaints are usually flares or slipping 2-3 shifts, or binding on the 3-4 shift.
In the previous installment, we covered the U140/U240 series transmissions and the slips and binds they run into. In this article, we’ll look at the U150/U250.
Whenever one of these transmissions comes into your shop, first perform a transmission memory reset procedure. Some aftermarket scan tools can perform the transmission memory reset, but it’s often best to use a factory Toyota/Lexus scan tool.
As we saw in the previous article, there’s a factory bulletin, TC002-03, that covers all models from 2000–2005 (figure 1).
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If you still have a slip or bind after performing the transmission reset, you’ll want to rule out the possibility of a faulty PCM. For that, follow the voltage tests for solenoids SL1, SL2, and SL3. Refer to the case connector and solenoid apply chart (figure 2) to follow the tests. Refer to a wiring diagram for wire colors.
We’ll be using diagrams for a 2008 Toyota Sienna. To avoid connector pin configuration and wire color confusion, refer to the appropriate information for the vehicle you’re working on.
SL1 SOLENOID TEST
- Put the car on a lift and raise the drive wheels off the ground.
- Backprobe terminals 6 and 13 in the case connector to check the SL1 solenoid.
- Connect your positive lead to terminal 6 and the negative lead to terminal 13 (figure 3).
- Set your voltmeter to VoltsDC.
- Start the engine and shift the transmission into drive. With the transmission in 1st gear, you should see about 6–7 volts on your voltmeter.
- Raise the engine RPM until the transmission shifts into 2nd gear. The voltage should drop to zero volts.
- Raise the engine RPM until the transmission shifts into 3rd gear. The voltage should jump back to about 6–7 volts again.
- Raise the engine RPM again until the transmission shifts into 4th gear. The voltage should drop to 0 volts again.
If the solenoid voltages change normally, the computer is controlling the SL1 solenoid properly. If not, suspect a computer problem.
SL2 SOLENOID TEST
- Put the car on a lift and raise the drive wheels off the ground.
- Backprobe terminals 5 and 12 in the case connector to check the SL2 solenoid.
- Connect your positive lead to terminal 5 and the negative lead to terminal 12 (figure 4).
- Set your voltmeter to VoltsDC.
- Start the engine and shift the transmission into drive. With the transmission in 1st gear, you should see about 6–7 volts on your voltmeter.
- Raise the engine RPM until the transmission shifts into 2nd gear. The voltage should remain between 6–7 volts.
- Raise the engine RPM until the transmission shifts into 3rd gear. The voltage should drop to zero. The SL2 voltage should remain at 0 volts in 4th and 5th gears.
If the solenoid voltages change normally, the computer is controlling the SL2 solenoid properly. If not, suspect a computer problem.
SL3 SOLENOID TEST
- Put the car on a lift and raise the drive wheels off the ground.
- Backprobe terminals 4 and 11 in the case connector to check the SL3 solenoid.
- Connect your positive lead to terminal 4 and the negative lead to terminal 11 (figure 5).
- Set your voltmeter to VoltsDC.
- Start the engine and shift the transmission into drive. With the transmission in 1st gear, you should see about 0 volts on your voltmeter.
- Raise the engine RPM until the transmission shifts into 2nd gear. The voltage should remain at 0 volts.
- Raise the engine RPM until the transmission shifts into 3rd gear. The voltage should remain at 0 volts.
- Raise the engine speed until the transmission shifts into 4th gear. The voltage should jump to about 6–7 volts.
If the solenoid voltages change normally, the computer is controlling the SL3 solenoid properly. If not, suspect a computer problem.
CHECK COMPUTER GROUNDS
Your next step should be to check the grounds to the computer (figure 6).
Connect your meter’s negative terminal to a chassis ground and backprobe the individual ground wires to the computer using the positive lead. With the engine running, each ground wire should have less than 0.1 volts.
Voltage greater than 0.1 indicates a faulty ground, and that could cause a variety of problems. Repair any ground problems as necessary. If all grounds are good, the computer is probably the culprit.
If the voltage checks for SL1, SL2, and SL3 are okay, you’ll need to check the solenoids and valve body. To understand which solenoid to consider, you’ll need to know what function each solenoid performs (figure 7). Solenoids SL1, SL2, and SL3 block solenoid modulator oil when energized; they allow modulator pressure through when de-energized.
Solenoid SL1 — A normally open (NO) linear solenoid. When the solenoid is energized in first gear, it blocks modulating pressure from passing through. The PCM turns the SL1 solenoid off during the 1-2 shift to regulate the B1 brake apply. The solenoid turns off during the 2-3 shift to regulate the B1 brake release and then turns off again for the 3-4 shift to regulate the B1 brake apply.
Solenoid SL2 — The SL2 solenoid is a normally open (NO) linear solenoid. When the SL2 solenoid is energized in first and second gears, it blocks modulator pressure from passing through. During the 2-3 shift, the PCM turns the solenoid off, opening the passage to regulate the C0 clutch apply.
Solenoid SL3 — The SL3 solenoid is a normally open (NO) linear solenoid. With the solenoid de-energized in first, second and third gears, modulator pressure passes through the solenoid to apply the C1 clutch. During the 3-4 shift, the PCM energizes the solenoid, which blocks the passage to regulate the release of the C1 clutch.
Now that you know which solenoid operates to control the shifts, it makes it easier to determine which solenoid to check or replace. The best way to check these solenoids is to use a solenoid test machine; energizing the solenoid on the bench isn’t a very effective test method.
VALVE BODY CHECKS
This leads to the next item: the valve body. Solenoid modulator pressure feeds the solenoids to control the shifts, so these solenoids need modulator pressure to operate. Another valve that commonly causes slips and binds is the clutch apply control valve.
Look for the solenoid modulator valve (figure 8) in the upper valve body, and the clutch apply control valve (figure 9) in the lower valve body. Both of these valves can wear; always examine them for wearing or sticking, to avoid slipping or binding shifts. There are valve repair kits and oversized valves available to correct these conditions.
So here are the easiest steps to identify the problems which can cause slips or binds in U150/U250 transmissions:
- Perform a transmission memory reset after every rebuild or repair.
- Test the solenoids to pinpoint whether you’re dealing with a solenoid or PCM failure.
- Check the grounds at the PCM.
- Look for solenoid or valve problems.
That covers the U140/U240 and U150/250 series transmissions. Always follow these simple steps to keep your customers’ vehicles where they belong… on the road.
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