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.
01J CVT: Diagnosing and Repairing Code 17090
A 2003 Audi A4 with an 01J continuously variable transmission (CVT) came to our shop. The customer complained that the vehicle was sluggish in forward and had no reverse and that this would take place only when all the lights in the gear indicator “lighted up and flashed.”
A Fly on the Wall
When transmission parts fail or have problems, I often think about the decisions made along the way that resulted in the problematic part being used in production. A common sight at many transmission benches these days is a “cracked” separator plate found in 2001 and newer 4R70W/4R75E units. There is more to this story than just the cracked plates discovered during the rebuild, and it started long ago when the decision was made to eliminate a valve-body stiffener plate. I would love to have been a fly on the wall back then, listening to the reasons why it was OK to eliminate the stiffener plate.
GM’s 2ML70 Hybrid Two-Mode Transmission – Part 2
As promised, we are back to take a look at the inside of this 2ML70 hybrid two-mode RWD transmission. When you look at the front of this transmission it almost appears to be receiving input torque from the gas engine through a conventional torque converter (Figure 1), but that is not the case. Power from the engine is delivered through a torque-damper assembly that is bolted to the crank and splines to the input shaft and pump. The reason for the front seal is that cooler return oil is supplied to the assembly through the pump to keep its damping parts lubricated.
More Torque-Converter Forensics
Try to imagine the difficult job tech-line technicians have. They are asked to decipher bits and pieces of information that may not be accurate and then come up with the correct answer. The information the technicians collected for the following two scenarios seemed to be as different as night and day. The information even originated in different countries. The amazing thing about these different complaints and symptoms was that they all had the same root cause.
Finding the cause of Honda 740 codes
Many converter shops have reported having Honda converters returned to their shops because of 740 codes. In most instances, the remedy was to install a new OEM converter.
Allison 1000/2000: TCC Cycling or Surge
In ATSG’s “Shifting Great in 2008” technical-training seminar we covered a complaint of TCC shuttle or surge with GM’s medium-duty trucks using Allison 1000/2000-series transmissions. This complaint usually occurs after converter replacement.
GM’s 2ML70 Hybrid Two-Mode Transmission
GM’s 2ML70 hybrid transmission (Figure 1) is a four-speed unit with fourth gear being overdrive. Applications include the 2008 Chevrolet Tahoe and GMC Yukon and the 6.0-liter 2009 Cadillac Escalade. It also was used for a short time in the 2009 5.7-liter Chrysler Aspen and Dodge Durango. BMW uses the two-mode 2ML70 in its ActiveHybrid X6, and Mercedes-Benz also uses it.
Toyota U341E/F
In the Import section of ATSG’s “Shifting Great in 2008” training seminar, one subject that was handled in the Toyota U341E/F segment of the seminar was the elusive code P0770. What makes this code so elusive is that it points to a fault for shift solenoid E. The technician tries to determine which is shift solenoid E and cannot. Nor can the technician determine whether the code indicates an electrical problem or a mechanical one.
TF-60SN Accumulator-Body Caution
So you’ve got it figured out. The cause of that TF-60SN converter issue you’ve been fighting has finally been narrowed down to wear in the lockup-clutch control bore. Well, before you reach for that pot of gold at the end of the rainbow, here are a couple of things you should know.
Checking for Cracks
Attendees at the 2009 Torque Converter Rebuilders Association (TCRA) seminar in Tennessee were introduced to a couple of interesting methods of checking torque-converter covers for cracks.
722.6/NAG 1
With the large number of 722.6 transmissions being used in both Mercedes vehicles and in Dodge and Jeep vehicles, where it is called the NAG 1, it is virtually certain that this transmission will end up in your shop for repairs. It may be that your shop refuses to work on Mercedes but Dodge and Jeep vehicles are all too welcome. And so it is in this way that if you have not worked on this transmission yet, you will. And it is not a bad unit to work on.
