Wayne Colonna, Author at Transmission Digest - Page 17 of 29
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A Twist of Fate

Aisin Seiki’s six-speed transmission used in medium-duty trucks is called by various names. It is the AS68RC in Dodge incomplete-chassis packages using L6 6.7-liter diesel engines. It is also called the AS6 in the Mitsubishi Fuso, the M036A6 in Nissan UDs and the A465 in Isuzu NPR trucks.

One of the common failures with this transmission is the stator turning in the pump (figures 1 and 2). A similar problem occurs with Allison 1000/2000 transmissions, in which it causes a TCC overheat and/or C1-clutch failure. You can quickly determine this by pulling the return cooling line. Oil comes out of the case fitting instead of the cooling line.

01J Gear-Ratio Error

During the recent Showpower Expo in Dallas, I was speaking with a good friend, Eddie Rose, from the UK who works on many 01J/0AW Multitronic continuously variable transmissions in Audi vehicles. He informed me of a problem he ran into while working on one of these that I just had to pass along to all those who are working on them here. This problem had Eddie stumped for a while but he finally sorted it out, and it was, of course, a simple solution to what had been a puzzling problem.

722.9 Pump Failure

A common and well-known failure with the 722.9 transmission is the way the pump bushing seizes to the converter neck (Figure 1).

Toyota’s U660E Flex Lockup Control

Toyota’s six-speed U660E (Figure 1) uses a converter-clutch strategy called flex lockup control. A partial explanation of this flex control strategy by Toyota follows:

During acceleration, flex lockup-clutch control operates when the transaxle is in second gear or higher and the shift lever is in the D, S6, S5 or S4 range position. During deceleration, it operates when the unit is in fourth gear or higher and the shift lever is in the D, S6, S5 or S4 range position.

Only One Way – the Right Way

Those of you who read my articles know that from time to time I may bore you with gear-train operation. It’s a part of the transmission’s operation that has always fascinated me. Understanding it goes a long way toward diagnosing various complaints, especially those involving noise.

In this instance I’m going to talk about a one-way-clutch device in a 62TE transmission (figures 1 & 2). But I first need to go through my boring explanation of the “foot bone being connected to the ankle bone” type details of the underdrive centerline shaft known as the underdrive compounder assembly (Figure 3).

A Hard Shift Fixed by a Gentle Squeeze

The RE4F03/4B transmission in several Nissan vehicles develops a hard 1-2 upshift as a result of uncontrolled line pressure. Sometimes code P0745 is stored for a problem in the line-pressure-control solenoid circuit. Replacing the solenoid assembly usually fixes the problem. But, the next time this happens to you, or you get to experience this for the first time, the fix may be as simple as gently squeezing a crimp.

Low/Reverse-Solenoid Circuit Fault Code P0750 (41)

Without question, aside from P1776 (47), one of the most-common trouble codes plaguing Dodge/Chrysler vehicles is P0750 (or 41), “Low/Reverse Solenoid Circuit error,” in 41TE-type transmissions (see Shift Pointers, October 2008). This is purely an electrical code and typically points to the solenoid, the wiring (which includes the connectors) from the solenoid body to the TCM, or the TCM itself. In so many instances on our technical hotline the cause has been a defective TCM. What becomes very frustrating is out-of-the-box remanufactured TCMs coughing up the same code as soon as they are installed; makes you think you missed something in your previous diagnosis.

Another One for the X-Files

Back in 2003, when Transmission Digest hosted Showpower in Charlotte, N.C., I did a presentation called “Odds with an End,” an array of transmission malfunctions featuring oddities from the “X” files.
To this day I still receive calls from some who attended this seminar saying, “Hey, Wayne, I’ve got another one you can add to your X-file list!”

The idea of labeling transmission malfunctions as fitting into an X-file category is the result of knowing what fixed the problem but having difficulty explaining why.

CVTs – Do I Rebuild Them or not?

The question of whether to rebuild a continuously variable transmission (CVT) has increased dramatically this past year on our technical hotline, and I thought I might risk making a few comments about this subject.

The call comes to our technical hotline a few different ways. The question has been: “Why are people saying you cannot rebuild CVTs?” or, “Is it worth trying to rebuild one of these” or, “What am I getting myself into if I try to rebuild one? What tools do I need?”

My answers to these questions follow.

An Interesting ‘Spin-off’ of a Hall-Effect Speed Sensor

Since the time of writing that article, it seems the Hall-effect style of sensor is favored among the manufacturers, most likely because of its reliability and the cost effectiveness of producing it. This sensor can be either a two- or three-wire design, with the frequency signal being generated by a magnetic wheel (ring) or by the teeth of a gear. The three-wire design consists of a voltage-supply wire, a ground and a signal wire. The two-wire design has a voltage-supply wire and a signal wire. For this two-wire sensor to work a resistor inside the TCM/PCM is wired to ground, allowing the voltage on the signal wire to drop when the rotating magnet is used to “chop” the sensor circuit and producing the signal pulse.

Which Came First, the Chicken or the Egg?

Codes setting codes is not a new concept in the automotive industry. An example of this in the world of transmissions occurs in Dodge vehicles using the 41TE transaxle. If it develops a gear-ratio-error code such as P0731/2/3/4, code 1790 “Fault Immediately After Shift” can also be present as a result of the gear-ratio code or codes. In fact, the explanation given by the manufacturer for setting this code is: This code is set if the associated speed ratio code is stored within 1.3 seconds after a shift.

Ford Code P2544

This article is a complement to this month’s Shift Pointers article titled “Which Came First, the Chicken or the Egg?” If you have yet to read it, after you’re finished reading here you may want to flip over to page 60 and give it a read.