Technically Speaking
- Subject: Design and operation
- Unit: 09D/TR-60SN
- Essential Reading: Rebuilder, Diagnostician
- Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor
The 09D/TR-60SN transmission (Figure 1), the rear-wheel-drive version of the front-wheel-drive 09G/TF-60SN transmission (Figure 2), is being used in the VW Touareg and Porsche Cayenne in the United States. The clutch-application chart in Figure 3 reveals the same clutch elements as in the 09G. If you save past issues of Transmission Digest, dig up the November and December 2008 issues and you can do a little comparison of the 09G with this 09D.
One of the nicer aspects of the 09G transmission from a diagnostic standpoint is that it provides pressure taps for every clutch as well as for TCC and lube. This 09D is no different, as you can see in figures 4, 5 and 6, and the similarities do not end here.
Just like the 09G, the 09D has two pass-through case connectors (Figure 7). The larger connector is for the solenoid circuits (Figure 8), and the smaller connector is for the speed sensors and pressure-switch circuits (Figure 9).
Figure 10 shows solenoid locations and identification, and Figure 11 identifies case passages.
The TCM uses the same software to control both these transmissions. Engine torque, transmission rpm and fluid temperature play major roles in controlling shift feel. There is also a strategy called “Skip Shift Control,” which is used to minimize shift busyness with these two six-speed transmissions yet still provide a smooth shift feel and good response. The Skip Shift Control has two basic strategies: a “Two-Step Skip Shift” strategy, used during certain driving conditions, will make a 1-3, 2-4 or 3-5 upshift; a “Three-Step Skip Shift” strategy is used to effect a 6-3 or 5-2 downshift.
These strategies are made possible by the way in which each clutch element is being controlled via linear solenoids. Figure 12 provides a basic solenoid on/off and clutch-application chart. When a linear clutch solenoid is turned off, its respective clutch is applied. Although the chart seems to indicate that this type of solenoid is on/off, they are pulse-width modulated as they come on and off, controlling both the apply and release of a clutch. Since these solenoids directly influence the apply and release of a clutch element, mechanical failure of these solenoids will indeed have an ill effect on shift feel.
As with the AW55-50SN and the 09G, these solenoids are not holding up to the task they have been assigned. Besides valve-body issues, solenoid failures are the main reason these vehicles visit shop bays across the country. All we need now is for the manufacturer to make the solenoids available for purchase.
For further information on the 09G transmission, ATSG has a Technician Guide in the bookstore and also is doing an in-depth look at the unit in its 2009 seminar.
Many thanks to the good folks at Alto for the use of the 09D transmission for this article.
