Double Jeopardy - Transmission Digest

Double Jeopardy

A 2002 Highlander 3.0L using the U140 transmission comes back to Pedro Seda’s shop in Puerto Rico. He had rebuilt it two years prior to its return where it had worked flawlessly during this time. Then, in an instant, it went from flawless to faulty. The transmission suddenly lost reverse and would no longer shift into fourth gear. When reverse was selected an engagement was felt yet the vehicle did not move in reverse.
Double Jeopardy

Shift Pointers

Author: Wayne Colonna
Subject Matter: U140
Issue: No reverse or 4th

Shift Pointers

  • Author: Wayne Colonna
  • Subject Matter: U140
  • Issue: No reverse or 4th

A 2002 Highlander 3.0L using the U140 transmission comes back to Pedro Seda’s shop in Puerto Rico. He had rebuilt it two years prior to its return where it had worked flawlessly during this time. Then, in an instant, it went from flawless to faulty. The transmission suddenly lost reverse and would no longer shift into fourth gear. When reverse was selected an engagement was felt yet the vehicle did not move in reverse.

Reference was then made to a component application chart to begin diagnosing the problem (Figure 1). The chart revealed the Direct/C2 clutch, the L-R/B3 brake and the UD/B3 brake are applied in reverse. For fourth gear the Forward/C1 clutch, the Direct/C2 clutch and the UD/C3 clutch are applied. So by a process of elimination it appears that the Direct/C2 clutch may be the problem.

A pan inspection was then made. At first it was a big surprise to find that it was very clean, especially for it having been on the road for two years. But then, thinking about how the problem occurred so suddenly, rather than a typical C2 clutch burn out, something related to the clutch must have snapped, sheared off or broke.

Once the rear cover was pulled and the C2 clutch assembly removed, there was nothing obviously wrong.

The drum, shaft, clutch hub, clutches, piston, pipes, seals, rings and cover were all in “pristine” condition.

At this point the valve body was removed and disassembled. When looking into the lower valve body where the check balls are located (Figure 2), a check ball was found split in two (figures 3 and 4). So one would think “viola,” we found the problem. The only problem is, the hydraulics provided in ATSG’s Tech Guide shows this ball as only controlling the flow rate in and out of the UD/B3 brake clutch.

The question to ask now is where did the other half of the ball travel to? The valve where this ball sits along side of is the 3-4 shift valve. A closer look at this valve showed that the other half of this ball is wedged underneath that valve. This caused it to be stuck in a partially stroked position (Figure 5).

When this valve is held closed by spring tension it allows line pressure to be routed to this check ball.

From this check ball line pressure is directed to the B3 Clutch, B3 accumulator and the B3 orifice control valve. The valve was stuck in such a way that it blocked pressure to the B3 clutch, causing the no-reverse condition. The C2 clutch and the B2 brake applied which is why an engagement was felt, yet without the B3 brake there is no reverse movement.

The question that should be asked now is, if the B3 clutches are not applying, how is it that it moves forward yet has no fourth gear?

Two reasons will satisfy this question:

  1. The B3 clutches are not necessary for it to move forward as the number 2 one-way-clutch will hold the UD planetary sun gear from turning clockwise. The B3 also holds the UD planetary sun gear from turning clockwise but also prevents it from turning counterclockwise.
    This will provide engine braking during lift foot deceleration.
  2. When the selector lever is placed into drive, additional line pressure is sent to the 3-4 shift valve and is blocked at the valve when it is held closed by spring tension. This valve remains closed for first, second and third gears. When it is stroked to make the 3-4 shift, this additional line pressure is then routed to the UD/C3 clutch for fourth gear. The 3-4 shift valve was jammed by the half ball in such a way that it blocked this pressure from applying the C3 clutch.

In conclusion, Pedro Seda was a victim of “double jeopardy.” A split ball jammed one valve causing two different problems.

You May Also Like

Trying to Stop the Wheel Hop on Ford Edge with 6F50 Transmission

The 2014 Ford Edge SEL with a 3.5L engine (figure 1) and a 6F50 transmission can also be equipped with an AWD system. This would include a Power Transfer Unit (PTU) attached to the transmission with a rear driveshaft going to the Read Differential Unit (RDU). The RDU comprises a differential assembly along with a

The 2014 Ford Edge SEL with a 3.5L engine (figure 1) and a 6F50 transmission can also be equipped with an AWD system. This would include a Power Transfer Unit (PTU) attached to the transmission with a rear driveshaft going to the Read Differential Unit (RDU). The RDU comprises a differential assembly along with a viscous coupling assembly controlled by an Active Torque Control (ATC) coupling solenoid. The system is designed to monitor vehicle conditions continuously and seamlessly adjust torque distribution between the front and rear wheels. When it is functioning correctly, there should be no perception of this taking place when launching or driving the vehicle. 

Sherlock Holmes Approach to an AB60 No-Move Situation

The effectiveness in diagnosing automatic transmission malfunctions is an art form. Although there are similarities among the wide varieties of transmissions on the road, each transmission has its own peculiarities. Aside from having mechanical, hydraulic, and electrical hardware systems to contend with, software/programming issues and various vehicle platforms make diagnostics much more difficult.  Related Articles –

ab60
GM 6T40 Pump Identification Guide

The 6T40 was introduced in 2008 for General Motors front-wheel-drive cars in the Chevrolet Malibu and has gone through several changes throughout its three generations, specifically in the pump area. The 6T40 is closely related to the more lightweight 6T30 and the heavier duty 6T45 and 6T50. Generation one started phasing out during the 2012

Seeing the Forest AND the Trees

They say that the proverbial phrase “I couldn’t see the forest for the trees” means that a person or organization cannot see the big picture because it focuses too much on the details. Related Articles – TASC Force Tips: Hydraulics Fundamentals: Check Valves – Shift Pointers: Mazda Sensitive to Pressure – Transmission Testing & Repairs:

The Manifold Pipeway

The Honda six-speed transmission has been on the bench of many specialty shops for one reason or another (figure 1). But, for those of you who have yet to lay your hands on one, mounted on the upper side of the unit is one of the largest, if not the largest solenoid and pressure switch

Other Posts
Shift Pointers: A 10R140 with a classic drivability complaint

A 2021 F-350 6.7L Super Duty using the 10R140 beast of a transmission recently came into Precision Auto Repair not upshifting when pulling a load only. On light throttle it would upshift, but not as high as tenth gear. Once the throttle was depressed it would downshift and no longer upshift. It displayed similar symptoms

Figure 2.
Shift Pointers: Where’s that fluid leak coming from?

A 2016 Honda CRV 2.4L (Figure 1), using a BLJA CVT 4WD transmission (Figure 2) comes in to a shop with a customer complaint of a leak. Related Articles – The powertrain aftermarket: Growing and global – 6R80 whirring noise: TCC slip or engine surge? – The torque converter can of worms: Lockup and aftermarket

Ford 8F35 maintenance tips: Planetary failure and no-pressure conditions

Our shop has had several vehicles come in with the Ford 8F35 transmission having planetary failure. Apparently, there was a run where the pinion needle bearings had a hardness problem (see Figure 1). Related Articles – The Subaru mystery burn – Multitasking: Sorting out multiple issues with the same vehicle – Chrysler RH/RE late shifts and

Figure 12.
Shift Pointers: A Chrysler 300 no-shift complaint

The case study has to do with a 2009 Chrysler 300 C 5.7L Nag1 RWD with 71,923 miles on it (see Figure 1, above). Related Articles – Ford 6R80 shift solenoid ‘E’ resistance change: How to tell the difference – Allison 1000 geartrain bind-up – How to get around non-serviceable GM 6T70/75 self-tapping pump screws