Something Amiss with Planetary System
You may remember back in the early days of the 41TE transmission (A604), the sun gear was known to shear off the shell. The result would be no reverse; it would take off in 1st gear but when it shifted into 2nd it would neutralize. With 2nd gear being failsafe, it would default to a neutral gear. The vehicle would then have no movement both forward and reverse. Once the ignition was cycled off to on, you could once again take off in 1st and shift into a no-move condition.
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.
Can a Bad Shift Solenoid Cause No Reverse with OK Upshifts?
It is not too often that you see a no-reverse concern caused by a bad solenoid or by a valve-body problem that does not affect any forward upshifts. Generally you’ll see this only on valve bodies that have a reverse-inhibit function, such as the 5L40 or JF506. There are always exceptions, though. We recently had an FNR5 do exactly that. In this instance it was a bad shift solenoid, but not one obviously connected to reverse.
62TE: No Reverse
A vehicle using a 62TE transmission comes into the shop with a no-reverse complaint but drives well going forward. Even with the solenoid pack disconnected it still has no reverse but drives forward in failsafe third gear well.
Under Pressure: Sticking solenoid inhibits reverse engagement
With the quantity and price of solenoids becoming a substantial additional investment in the price of a transmission reman, testing and reclaiming the solenoids has become mandatory.
No-Reverse Complaint Presents Diagnostic Challenge
As I read about the operating strategy of the solenoids, I learned that the PCM commands solenoids A, B and E (Figure 1) when reverse gear is selected. Now I could see that solenoid E has an important role in reverse-gear engagement, and I was starting to think I had cleared at least one hurdle. If solenoid E is inoperable, oil will not be directed to engage reverse. I was now certain that I had found a common link to the problems that the owner experienced.
AW55-50: No Reverse; 09G/09K/09M: No Movement
I recently received a phone call from a shop that was working on a 2001 Volvo with an AW 55-50 transmission. The vehicle would not move when shifted from Park to Reverse. If the selector was first put into Drive then moved to Reverse, engagement was normal. The manual linkage was checked, confirming that the manual valve was in the reverse position.
Making the Car Disappear
A 1997 Audi A4 Quattro 1.8L turbo (ZF 5HP19) with a complaint that the transmission lost reverse once it was warmed up.
This transmission has a history of chronic reverse problems. The vehicle was scanned with a MODIS and presented the following codes: 00652, 18010 and P1602.
As valves and bores begin to wear and allow leakage, the easiest path for the leak is to exhaust. Two things happen as a result of this wear-induced exhaust leak. First, the leak allows a pressure drop, which is loss of control pressure. Valves or components no longer move, apply or respond as intended. Second, the amount of exhausted fluid and, therefore, the amount of air entering the sump are increased. The amount of aeration can easily surpass the sump’s ability to dissipate the air before the pump picks it up. The minimal sump capacity of the 5L40-E makes it especially vulnerable to this problem.
Catching a Brake on Shift Problems
A 2001 Nissan Altima was brought to a transmission shop with the complaint that the shifter would not move into reverse or park. The customer explained that the vehicle performed just fine when cold but occasionally refused to go into reverse or park after warming up. The shop performed its routine pre-checks and then road-tested the vehicle. The pre-checks didn’t show any codes present (not even a history code), and the technician wasn’t able to reproduce the condition on the road test. The customer was asked to leave the vehicle for further evaluation.
Have you ever built a unit that went out running absolutely fantastic but came back with a problem only a month or two later? Maybe you were so good to that transmission that it was missing you and wanted to come back for a visit!
Moving Forward with No Reverse
It is quite a surprise for a technician to learn that a malfunctioning TCC solenoid could cause a slipping in reverse or loss of reverse with 4L30-E transmissions.