On the Road - April - 2017

Correcting Toyota U140/U240 Shift Troubles

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 even 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 this issue, we’ll cover the U140/U240 series transmissions and the slips and binds they run into. We’ll look at the U150/U250 in a later article.

Back in the early 2000s, the Toyota Rav4 had some serious computer issues with harsh shifts and possible solenoid trouble codes. But what if you aren’t working on a Rav4? Similar issues can and have occurred. What should you do about that?

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.

There’s a factory bulletin, TC002-03 that covers all models from 2000 – 2005 (figure 1).

If you still have a slip or bind after performing the transmission reset, next you’ll want to rule out the possibility of a faulty PCM. For that, follow the voltage tests for solenoids SL1 and SL2. 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 RAV4. 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 5 and 10 in the case connector for the SL1 solenoid. Connect your positive lead to terminal 5 and the negative lead to terminal 10. (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 5–6 volts on your voltmeter.
  • Raise the engine speed until the transmission shifts into 2nd gear. The voltage should drop to zero volts.
  • Raise the engine speed until the transmission shifts into 3rd gear. The voltage should jump back to about 5–6 volts, but only until the shift is complete; then it should drop back to zero.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 4 and 9 in the case connector for the SL2 solenoid. Connect your positive lead to terminal 4 and the negative lead to terminal 9. (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 5–6 volts on your voltmeter.
  • Raise the engine speed until the transmission shifts into 2nd gear. The voltage should remain between 5–6 volts.

Raise the engine speed until the transmission shifts into 3rd gear. The voltage should drop to zero.
NOTE: Both SL1 and SL2 should drop to zero at the same time when the transmission completes the 2-3 shift.

If the solenoid voltages change normally, the computer is controlling the solenoids properly. If not, your next step should be to check the grounds to the computer (figure 5).

Connect your meter’s negative terminal to a chassis ground and backprobe the individual ground wires to the computer using the positive lead. Each ground wire should have less than 0.1 volts with the engine running.

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 and SL2 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 6).

Solenoids SL1 and SL2 block solenoid modulator oil when the solenoid is energized; the solenoid will perform its respective function when the solenoid is de-energized, allowing modulator pressure to flow through the solenoid.

Solenoid SL1 — A normally applied (NA) linear solenoid. When the solenoid is energized in first gear, it blocks solenoid modulator pressure passing through the solenoid.

The PCM turns the SL1 solenoid off during the 1-2 shift to regulate B1 brake apply. During the 2-3 shift, the PCM turns the SL1 solenoid on for a moment to exhaust the B1 brake during the 2-3 upshift.

Solenoid SL2 — The SL2 solenoid is a normally applied (NA) linear solenoid. When the SL2 solenoid is energized in first and second gear, it blocks modulator pressure. During the 2-3 shift, the PCM turns the solenoid off to regulate C2 clutch apply.

Now that you know which solenoid operates to control the shift, 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 method to test them.

This leads us 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 (figure 7).

Look for the solenoid modulator valve and the clutch control valve 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 causing slips or binds in U140/U240 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.

Next time we’ll cover similar conditions with the U150/250 series transmissions. Always follow these simple steps to keep your customers’ vehicles where they belong… on the road.