January 2009 Archives - Transmission Digest
January 2009 Issue

Issue Summary:

A break or short in wiring or possible failure of the tow/haul mode switch can cause tow/haul mode to be inactive and may set code B2722.

Loss of AFL-valve pressure can result in a neutral condition either during or immediately after the shift to fourth gear in a 4L80-E.

A Saturn Vue with the AF33-5 transmission in limp mode with code P0717 set may have a faulty input-speed sensor.

Tests Explain Why Beetle Won’t Run

I finally find a one-page black-and-white wiring diagram that’s close in one of my information services’ archives section. I start this “project” with expectations of finding the usual extra problems created by the well-meaning “wannabe” technicians through whose hands this car has passed since its demise some four years ago, according to its registration. It’s also had two different owners since it last ran on its own systems. I find an overfull crankcase with the smell of stale fuel, carboned-up spark plugs and a sensor connector terminal with “baby bird mouth” syndrome.

Want to Be a Leader? Then Lead!

Here’s where your role as a leader comes into play in several ways. You’ll need to lead your customers to make the purchases of your services that they require, you’ll have to lead your employees to a sense of well-being and excitement about their futures in the industry, and you will want to take the lead in your communities by setting an example of enthusiasm for other small businesses to follow. After all, recessions end when enough of us believe they are over. If your enthusiasm is contagious you may be able to help hasten the process.

Proving a RAV4 PCM to Be Defective

Recently we had a 2001 Toyota AWD RAV4, with 114,000 miles on the odometer, come into the shop for transmission diagnosis and repair. It had a bind feeling on the 1-2 shift and a flare when it shifted to third, no codes and burnt fluid. Once it was in third and then fourth, it would drive fine, and the lockup also functioned properly.

BorgWarner 4473 and 4410 Transfer Cases

Viscous couplings have been used in automotive applications for many years in transfer cases, rear-end differentials, torque converters and radiator cooling fans. Although the concept is not new, the viscous coupling is not well understood in the repair industry and creates a number of diagnostic and repair issues. Part of this problem occurs because all viscous couplings are by necessity sealed units that cannot be inspected. The second part of the problem is a lack of understanding of how they work, principal causes of failure and the proper diagnostic path to follow.


By the time they arrive, they are well-seasoned units, although not necessarily what you would consider high-mileage. Although these automakers use the same transmission, there will be variations in the shafts, drums, converters, valve bodies and TCM calibration. The 2-3/3-2 shift issues are common, regardless of brand, and may be accompanied by codes P0780/785 or P0745.

Which Planet Are You On?

As most rebuilders know, in 1997 the 4L80-E went to a center-gearbox lubrication system by relocating the cooler return line from the pump to the center support. As a result, many internal hard parts were redesigned to accommodate this new lubrication system, as illustrated in figures 1 through 5 taken from an ATSG bulletin.

TCC Apply

The debate about whether to use a grooved or smooth friction lining to rebuild a converter originally equipped with a grooved lining has been going on since the day grooved linings first arrived at torque-converter shops. Those advocating a grooved replacement lining always seemed to have the upper hand because they used the very strong argument that “it is the same as OE.”