June 2010 Archives - Transmission Digest
Mount Up, Partner

The transmission in this scenario is the VT25 CVT in the Saturn Vue. Figure 1 shows the location of the top transmission mount. The bolt holes and the bolts that secure the mount to the transmission case are different lengths, which means the bolts can be installed in the wrong holes.

GM’s Hybrid Two-Mode 2MT70 Transmission, Part 1

As mentioned and promised in the February issue of Transmission Digest, we will take a quick peek at the front-wheel-drive version of the longitudinally mounted two-mode 2ML70 transmission, called the 2MT70 (Figure 1).

June 2010 Issue

In This Issue
4L60/65/70-E: Pump and input-shaft usage
GM 6L80: Slips in forward, sets DTC P2728
Freightliner/Dodge Sprinter: 722.6/NAG1 limp mode

Issue Summary:

Incorrect interchange of pump covers and input shafts in 1997-2006 GM vehicles with 4L60/65/70-E transmissions can cause a variety of problems.

GM vehicles equipped with the 6L80 transmission may exhibit a complaint of a slip on takeoff in the forward ranges, typically in first gear, and code P2723 or P2728 may be present.

On Freightliner/Dodge Sprinter vans with roof-mounted electric ventilation fans, the transmission may go into limp mode when the fans turn on.

Bucking the Trend, or How to be Successful in a Down Market

Trends in our business have changed dramatically so that customers can price-shop or buy parts or reman units on the Internet and then seek someone to install them. This puts a lot of pressure on price as the most-important factor in the business equation, with quality becoming a less-important factor in the decision. It is very easy to get caught up in this squeeze between what cheap is and what good is. There is a difference between spending less money on repairs and buying a better-quality job. That difference is “value added,” and it is vital that you know and understand the difference and explain that to your customers, and that you practice the same policies in your business purchasing.

A Case of Mistaken Identity

Those of us in the business have seen all different kinds of oddball installations and strange diagnoses that make absolutely no sense. There are so many variables that can contribute to a problem, and finding the root cause is an ongoing challenge for all of us. To complicate things even further, if you don’t have the background story on the vehicle you’re trying to fix, you’re working with assumptions that can easily get you into trouble. This story is an example of one such repair challenge.

Preventing 48RE Transmission Throttle-Valve-Actuator Codes

In 2005, Dodge started using a transmission throttle-valve actuator (TTVA) instead of a TV cable on the 48RE diesel 2500 and 3500 Ram trucks. The actuator, attached to the case above the throttle-valve shaft, includes two potentiometers that provide input to the ECM as well as a DC motor that responds to ECM output. The bottom of the TTVA shaft features a D-shaped opening that fits onto the throttle shaft, allowing the actuator to mechanically stoke the TV valve and ultimately control transmission throttle pressure.

722.6 Cold Stall/Shudder, Part II

In last month’s article, technicians found that centrifugal force acting on oil trapped between the TCC piston and cover in the 722.6 converters was applying the clutch on cold startup. They also learned that the cold-stall issue could be eliminated by forcing the oil out of the cavity between the piston and cover. Finding the root cause of the cold-stall issue – and the subsequent fix – solved many other customer complaints and symptoms, including downshift shudders and tugging sensations.

Serviceability Report: Nissan Altima

In 1993, Nissan discontinued its much-criticized Stanza, replacing it with the U.S.-made Altima, which, like the Stanza, is a compact car. The very first Altima rolled off the assembly line June 15, 1992, as a 1993 model. All Altimas were built in Smyrna, Tenn., until June 2004, when Nissan’s Canton, Miss., plant began producing additional Altimas to meet high demand.

They Just Don’t Care

This story is from the “strange but true” file. It begins with the concept that customers should and often do allow us to fix many, if not all, of the problems we find with their vehicles. We operate our businesses on the basis of that assumption, but every now and then we are thrown a big sweeping curve ball.